USMLE Step 3 Audio Crash Course

USMLE III Complete Test Prep and Review for the United States Medical Licensure Examination Step 3 (USMLE III)

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Table of Contents Preface ..............................................................................................................................................1 Chapter 1: Infectious diseases ............................................................................................................5 Sepsis ...................................................................................................................................................... 5 Osteomyelitis .......................................................................................................................................... 5 Head and Neck Infections ....................................................................................................................... 6 Otitis Externa .......................................................................................................................................... 7 Otitis Media ............................................................................................................................................ 7 Sinusitis ................................................................................................................................................... 7 Pharyngitis .............................................................................................................................................. 8 Influenza ................................................................................................................................................. 8 Skin Infections ......................................................................................................................................... 8 Impetigo .............................................................................................................................................. 8 Erysipelas ............................................................................................................................................ 9 Cellulitis .............................................................................................................................................. 9 Folliculitis, Carbuncles, and Furuncles ................................................................................................ 9 Fungal Infections ............................................................................................................................... 10 Sexually Transmitted Diseases .............................................................................................................. 10 Urethritis ........................................................................................................................................... 10 Cervicitis............................................................................................................................................ 10 Pelvic Inflammatory Disease (PID) .................................................................................................... 10 Epididymitis and Orchitis .................................................................................................................. 11 Ulcerative Genital Diseases ............................................................................................................... 11 Syphilis .............................................................................................................................................. 11 Genital Warts .................................................................................................................................... 12 Urinary Tract Infections ........................................................................................................................ 12 Cystitis............................................................................................................................................... 12 Acute Pyelonephritis ......................................................................................................................... 13 Prostatitis .......................................................................................................................................... 13 HIV/AIDS ........................................................................................................................................... 13 Opportunistic Infections ................................................................................................................... 14

Infective Endocarditis........................................................................................................................ 15 Key Takeaways ...................................................................................................................................... 16 Quiz ....................................................................................................................................................... 16 Chapter 2: Allergy and Immunology.................................................................................................. 22 Anaphylaxis ........................................................................................................................................... 22 Angioedema .......................................................................................................................................... 22 Allergic Rhinitis ..................................................................................................................................... 23 Atopic Dermatitis .................................................................................................................................. 23 Primary Immunodeficiency States ........................................................................................................ 24 Severe Combined Immunodeficiency Disease (SCID) ........................................................................ 24 Common Variable Immunodeficiency Disease (CVID) ....................................................................... 24 X-Linked Agammaglobulinemia (Bruton syndrome) ......................................................................... 24 IgA Deficiency ................................................................................................................................... 25 Hyper IgE Syndrome.......................................................................................................................... 25 Hypersensitivity Reactions .................................................................................................................... 25 Key Takeaways ...................................................................................................................................... 26 Quiz ....................................................................................................................................................... 26 Chapter 3: Tropical, Fungal, and Animal-borne Diseases.................................................................... 32 Animal-Borne Diseases ......................................................................................................................... 32 Leptospirosis ..................................................................................................................................... 32 Tularemia .......................................................................................................................................... 32 Cysticercosis ...................................................................................................................................... 33 Trichinellosis ..................................................................................................................................... 33 Plague ............................................................................................................................................... 33 Strongyloides Infection ......................................................................................................................... 34 Chagas Disease...................................................................................................................................... 34 Brucellosis ............................................................................................................................................. 35 Anthrax ................................................................................................................................................. 35 Bartonella ............................................................................................................................................. 35 Tick-Borne Diseases .............................................................................................................................. 36 Lyme Disease .................................................................................................................................... 36 Babesiosis ......................................................................................................................................... 36 Ehrlichia/Anaplasmosis ..................................................................................................................... 36

Malaria .............................................................................................................................................. 37 Fungal and Atypical Pulmonary Diseases .............................................................................................. 37 Nocardiosis ....................................................................................................................................... 37 Actinomycosis ................................................................................................................................... 38 Histoplasmosis .................................................................................................................................. 38 Coccidiomycosis ................................................................................................................................ 38 Blastomycosis ................................................................................................................................... 38 Mucormycosis (Zygomycosis) ........................................................................................................... 39 Aspergillosis ...................................................................................................................................... 39 Candida auris Infection ..................................................................................................................... 39 Tropical Diseases and Parasites ............................................................................................................ 40 Dengue Fever .................................................................................................................................... 40 Ebola Virus ........................................................................................................................................ 40 Chikungunya ..................................................................................................................................... 40 Zika Virus........................................................................................................................................... 40 Crimean-Congo Hemorrhagic Fever .................................................................................................. 41 Leishmaniasis .................................................................................................................................... 41 Echinococcus ..................................................................................................................................... 41 Cimex Bites (Bedbugs) ...................................................................................................................... 41 Middle Eastern Respiratory Syndrome (MERS) ................................................................................. 42 Cholera .............................................................................................................................................. 42 Key Takeaways ...................................................................................................................................... 42 Quiz ....................................................................................................................................................... 43 Chapter 4: Cardiology....................................................................................................................... 49 Ischemic Heart Disease ......................................................................................................................... 49 Acute Coronary Syndrome .................................................................................................................... 50 Chronic Angina ...................................................................................................................................... 50 Managing Lipids .................................................................................................................................... 51 Congestive Heart Failure ....................................................................................................................... 51 Valvular Heart Disease .......................................................................................................................... 52 Aortic Stenosis ...................................................................................................................................... 53 Aortic Regurgitation .............................................................................................................................. 54 Mitral Stenosis ...................................................................................................................................... 54

Mitral Regurgitation (MR) ..................................................................................................................... 54 VSD and ASD ......................................................................................................................................... 55 Cardiomyopathy ................................................................................................................................... 55 Dilated Cardiomyopathy ................................................................................................................... 55 Hypertrophic Cardiomyopathy.......................................................................................................... 56 Restrictive Cardiomyopathy .............................................................................................................. 56 Takotsubo Cardiomyopathy .............................................................................................................. 56 Pericardial Diseases .............................................................................................................................. 56 Pericarditis ........................................................................................................................................ 56 Pericardial Tamponade ..................................................................................................................... 57 Constrictive Pericarditis .................................................................................................................... 57 Aortic disease .................................................................................................................................... 57 Peripheral Arterial Disease................................................................................................................ 57 Arrhythmias .......................................................................................................................................... 58 Atrial Fibrillation ............................................................................................................................... 58 Atrial Flutter ...................................................................................................................................... 58 Multifocal Atrial Tachycardia ............................................................................................................ 59 Supraventricular Tachycardia............................................................................................................ 59 Wolff-Parkinson-White (WPW) Syndrome ........................................................................................ 59 Ventricular Tachycardia and VFib...................................................................................................... 59 Evaluation of Syncope ....................................................................................................................... 59 Key Takeaways ...................................................................................................................................... 60 Quiz ....................................................................................................................................................... 60 Chapter 5: Endocrinology ................................................................................................................. 66 Diabetes Mellitus .................................................................................................................................. 66 Diabetic Ketoacidosis ............................................................................................................................ 67 Diabetic Complications ......................................................................................................................... 67 Thyroid Disease..................................................................................................................................... 68 Calcium Disorders ................................................................................................................................. 69 Hypercalcemia .................................................................................................................................. 69 Hypocalcemia .................................................................................................................................... 70 Cushing Syndrome ............................................................................................................................ 70 Addison Disease ................................................................................................................................ 70

Pheochromocytoma .......................................................................................................................... 71 Congenital Adrenal Hyperplasia (CAH) .............................................................................................. 71 Prolactinoma ..................................................................................................................................... 71 Acromegaly ....................................................................................................................................... 72 Key Takeaways ...................................................................................................................................... 72 Quiz ....................................................................................................................................................... 72 Chapter 6: Pulmonology ................................................................................................................... 78 Asthma .................................................................................................................................................. 78 COPD/Emphysema ................................................................................................................................ 79 Alpha-1 Antitrypsin Disease .................................................................................................................. 81 Bronchiectasis ....................................................................................................................................... 81 Interstitial Lung Disease (ILD)................................................................................................................ 81 Bronchiolitis Obliterans Organizing Pneumonia (BOOP) ....................................................................... 82 Sarcoidosis ............................................................................................................................................ 82 Pulmonary Hypertension ...................................................................................................................... 83 Pulmonary Embolism ............................................................................................................................ 83 Pleural Effusion ..................................................................................................................................... 84 Sleep Apnea .......................................................................................................................................... 85 Allergic Bronchopulmonary Aspergillosis (ABPA) .................................................................................. 85 ARDS ..................................................................................................................................................... 85 Pneumonia ............................................................................................................................................ 85 Tuberculosis (TB)................................................................................................................................... 86 Key Takeaways ...................................................................................................................................... 87 Quiz ....................................................................................................................................................... 87 Chapter 7: Rheumatology................................................................................................................. 93 Rheumatoid Arthritis (RA) ..................................................................................................................... 93 Seronegative Spondyloarthropathies ................................................................................................... 94 Ankylosing Spondylitis (AS) ................................................................................................................... 95 Reactive Arthritis .................................................................................................................................. 95 Psoriatic Arthritis .................................................................................................................................. 95 Juvenile Rheumatoid Arthritis ............................................................................................................... 95 Osteoarthritis (OA) ................................................................................................................................ 95 Systemic Lupus Erythematosus (SLE) .................................................................................................... 96

Sjogren Syndrome ................................................................................................................................. 97 Scleroderma (Systemic Sclerosis) .......................................................................................................... 97 CREST Syndrome ................................................................................................................................... 98 Eosinophilic Fasciitis.............................................................................................................................. 98 Polymyositis (PM) and Dermatomyositis (DM) ..................................................................................... 98 Mixed Connective Tissue Disease (MCTD) ............................................................................................ 99 Polymyalgia Rheumatica ....................................................................................................................... 99 Vasculitis ............................................................................................................................................... 99 Polyarteritis Nodosa.............................................................................................................................. 99 Churg-Strauss Syndrome (Eosinophilic Granulomatosis) .................................................................... 100 Temporal Arteritis ............................................................................................................................... 100 Takayasu Arteritis ............................................................................................................................... 100 Cryoglobulinemia ................................................................................................................................ 100 Gout .................................................................................................................................................... 100 Pseudogout ......................................................................................................................................... 101 Septic Arthritis .................................................................................................................................... 101 Paget Disease of the Bone .................................................................................................................. 101 Osteoporosis ....................................................................................................................................... 101 Key Takeaways .................................................................................................................................... 102 Quiz ..................................................................................................................................................... 102 Chapter 8: Hematology .................................................................................................................. 108 Anemia ................................................................................................................................................ 108 Sickle Cell Disease ............................................................................................................................... 109 Autoimmune Hemolysis ...................................................................................................................... 110 Cold-induced Hemolysis (Cold Agglutinins)......................................................................................... 110 Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency .................................................................. 110 Hereditary Spherocytosis .................................................................................................................... 110 Hemolytic Uremic Syndrome (HUS) and Thrombotic Thrombocytopenic Purpura (TTP) .................... 110 Paroxysmal Nocturnal Hemoglobinuria (PNH) .................................................................................... 111 Leukemias ........................................................................................................................................... 111 Myelodysplasia ................................................................................................................................... 111 Chronic Myelogenous Leukemia (CML) ............................................................................................... 111 Chronic Lymphocytic Leukemia .......................................................................................................... 112

Hairy Cell Leukemia............................................................................................................................. 112 Polycythemia Vera .............................................................................................................................. 112 Essential Thrombocythemia................................................................................................................ 113 Multiple Myeloma .............................................................................................................................. 113 Waldenstrom Macroglobulinemia ...................................................................................................... 113 Lymphoma .......................................................................................................................................... 113 Coagulation Disorders ......................................................................................................................... 114 Von Willebrand Disease (VWD) ....................................................................................................... 114 Idiopathic Thrombocytopenic Purpura (ITP) ................................................................................... 114 Platelet Function Disorders ............................................................................................................. 114 Hypercoagulable States .................................................................................................................. 115 Key Takeaways .................................................................................................................................... 115 Quiz ..................................................................................................................................................... 115 Chapter 9: Gastroenterology .......................................................................................................... 122 Esophageal Disorders .......................................................................................................................... 122 Evaluating Epigastric Pain ................................................................................................................... 124 Stress Ulcer Prophylaxis ...................................................................................................................... 124 Zollinger-Ellison Syndrome ................................................................................................................. 124 Inflammatory Bowel Disease .............................................................................................................. 125 Diarrhea .............................................................................................................................................. 125 Malabsorption .................................................................................................................................... 126 Celiac Disease ..................................................................................................................................... 126 Chronic Pancreatitis ............................................................................................................................ 127 Irritable Bowel Syndrome ................................................................................................................... 127 Colon Cancer ....................................................................................................................................... 127 Diverticular Disease ............................................................................................................................ 127 GI Bleeding .......................................................................................................................................... 128 Constipation........................................................................................................................................ 129 Dumping Syndrome ............................................................................................................................ 129 Acute Pancreatitis ............................................................................................................................... 129 Hepatitis .............................................................................................................................................. 129 Liver Cirrhosis...................................................................................................................................... 130 Key Takeaways .................................................................................................................................... 132

Quiz ..................................................................................................................................................... 132 Chapter 10: Neurology ................................................................................................................... 138 TIAs and Strokes.................................................................................................................................. 138 Seizure and Seizure Disorder .............................................................................................................. 139 Parkinson’s Disease............................................................................................................................. 140 Multiple Sclerosis ................................................................................................................................ 140 Alzheimer Disease (AD) ....................................................................................................................... 141 Pick Disease (Frontotemporal Dementia) ........................................................................................... 141 Creutzfeldt-Jakob Disease (CJD) .......................................................................................................... 141 Lewy Body Dementia .......................................................................................................................... 141 Normal Pressure Hydrocephalus......................................................................................................... 141 Huntington Disease ............................................................................................................................. 142 Headache ............................................................................................................................................ 142 Dizziness and Vertigo .......................................................................................................................... 142 CNS Infections ..................................................................................................................................... 143 Bacterial Meningitis ............................................................................................................................ 143 Cryptococcus Meningitis ..................................................................................................................... 144 Other Causes of Meningitis ................................................................................................................. 144 Encephalitis ......................................................................................................................................... 145 Brain Abscess ...................................................................................................................................... 145 Head Trauma ...................................................................................................................................... 145 Subarachnoid Hemorrhage (SAH) ....................................................................................................... 146 Spine Disorders ................................................................................................................................... 146 Peripheral Neuropathies ..................................................................................................................... 147 Myasthenia Gravis .............................................................................................................................. 147 Key Takeaways .................................................................................................................................... 147 Quiz ..................................................................................................................................................... 148 Chapter 11: Nephrology ................................................................................................................. 154 Acute Renal Failure ............................................................................................................................. 154 Glomerulonephritis ............................................................................................................................. 155 Nephrotic Syndrome ........................................................................................................................... 156 Miscellaneous Primary Renal Diseases ............................................................................................... 157 Proteinuria .......................................................................................................................................... 157

End-Stage Renal Disease (ESRD) ......................................................................................................... 157 Hypernatremia .................................................................................................................................... 158 Hyponatremia ..................................................................................................................................... 158 SIADH .................................................................................................................................................. 158 Hyperkalemia ...................................................................................................................................... 159 Hypokalemia ....................................................................................................................................... 159 Magnesium-related Disorders ............................................................................................................ 159 Metabolic Acidosis .............................................................................................................................. 160 Metabolic Alkalosis ............................................................................................................................. 161 Cystic Disease...................................................................................................................................... 161 Hypertension ...................................................................................................................................... 161 Key Takeaways .................................................................................................................................... 162 Quiz ..................................................................................................................................................... 162 Chapter 12: Oncology ..................................................................................................................... 168 Breast Cancer Screening ..................................................................................................................... 168 Hormone Inhibition for Breast Cancer ................................................................................................ 168 Colon Cancer ....................................................................................................................................... 168 Lung Cancer ........................................................................................................................................ 169 Cervical Cancer ................................................................................................................................... 170 Prostate Cancer................................................................................................................................... 170 Ovarian Cancer.................................................................................................................................... 171 Testicular Cancer ................................................................................................................................ 171 Key Takeaways .................................................................................................................................... 171 Quiz ..................................................................................................................................................... 171 Chapter 13: Preventive Medicine .................................................................................................... 177 Cancer Prevention .............................................................................................................................. 177 Immunizations in Children .................................................................................................................. 177 Other Vaccinations.............................................................................................................................. 178 Miscellaneous Primary Screening Tests .............................................................................................. 179 Key Takeaways .................................................................................................................................... 180 Quiz ..................................................................................................................................................... 181 Chapter 14: Dermatology ............................................................................................................... 186 Bullous Diseases of the Skin ................................................................................................................ 186

Pemphigus Vulgaris (PV) ..................................................................................................................... 186 Bullous Pemphigoid (BP) ..................................................................................................................... 186 Pemphigus Foliaceus (PF).................................................................................................................... 186 Porphyria Cutanea Tarda (PCT) ........................................................................................................... 187 Urticaria .............................................................................................................................................. 187 Morbilliform Rash ............................................................................................................................... 188 Erythema Multiforme ......................................................................................................................... 188 Stevens-Johnson Syndrome (SJS) ........................................................................................................ 188 Toxic Epidermal Necrolysis (TEN) ........................................................................................................ 188 Fixed Drug Reaction ............................................................................................................................ 188 Erythema Nodosum ............................................................................................................................ 189 Skin Infections ..................................................................................................................................... 189 Fungal Infections ............................................................................................................................. 189 Bacterial Infections ............................................................................................................................. 190 Viral Skin Infections............................................................................................................................. 191 Herpes Simplex ............................................................................................................................... 191 Herpes Zoster (Varicella) ................................................................................................................. 191 Sexually Transmitted Diseases (STDs) ................................................................................................. 192 Human Papillomavirus .................................................................................................................... 192 Syphilis ............................................................................................................................................ 192 Scabies ............................................................................................................................................ 193 Pediculosis ...................................................................................................................................... 193 Lyme Disease .................................................................................................................................. 193 Toxin-related Skin Diseases................................................................................................................. 193 Toxic Shock Syndrome (TSS)............................................................................................................ 193 Staphylococcal Scalded Skin Syndrome (SSSS) ................................................................................ 194 Anthrax ........................................................................................................................................... 194 Benign Lesions and Skin Cancer ...................................................................................................... 194 Eczematous Disorders ......................................................................................................................... 195 Psoriasis .......................................................................................................................................... 195 Asteatotic Dermatitis ...................................................................................................................... 196 Atopic Dermatitis ............................................................................................................................ 196 Seborrheic Dermatitis ..................................................................................................................... 196

Contact Dermatitis .......................................................................................................................... 197 Pityriasis Rosea ............................................................................................................................... 197 Acne ................................................................................................................................................ 198 Rosacea ........................................................................................................................................... 198 Key Takeaways .................................................................................................................................... 198 Quiz ..................................................................................................................................................... 199 Chapter 15: Surgery ....................................................................................................................... 205 General Surgery .................................................................................................................................. 205 The Acute Abdomen ....................................................................................................................... 205 Inflammatory Conditions of the Abdomen ..................................................................................... 206 Ischemia .......................................................................................................................................... 207 Abdominal Abscess ......................................................................................................................... 207 Hepatobiliary Disease ..................................................................................................................... 207 Gall Stone Diseases ......................................................................................................................... 208 Sphincter of Oddi Dysfunction (SOD) .............................................................................................. 208 Anorectal Disease ............................................................................................................................... 208 Fecal Incontinence .......................................................................................................................... 208 Anal Fissure ..................................................................................................................................... 209 Preoperative and Postoperative Care ............................................................................................. 209 Cardiac Risk Index ........................................................................................................................... 209 Postoperative Complications .......................................................................................................... 210 Pediatric Surgery ................................................................................................................................. 211 Disorders at Birth ............................................................................................................................ 211 Surgical Conditions prior to 2 Months of Age ................................................................................. 212 Diseases seen Late in Infancy .......................................................................................................... 212 Orthopedic Surgery ......................................................................................................................... 213 Urologic Surgical Conditions ............................................................................................................... 214 Testicular Torsion ............................................................................................................................ 214 Orchitis/Epididymitis....................................................................................................................... 214 Acute Epididymitis .......................................................................................................................... 215 Urological Obstructions .................................................................................................................. 215 Abdominal Wall Hernias ................................................................................................................. 215 Vascular Surgery ................................................................................................................................. 216

Subclavian Steal Syndrome ............................................................................................................. 216 Abdominal Aortic Aneurysm ........................................................................................................... 216 Peripheral Vascular Disease ............................................................................................................ 217 Key Takeaways .................................................................................................................................... 217 Quiz ..................................................................................................................................................... 217 Chapter 16: Pediatrics .................................................................................................................... 224 Newborn Care and Newborn Diseases ................................................................................................ 224 Infant of a Diabetic Mother ................................................................................................................ 224 Respiratory Distress in the Neonate ................................................................................................... 225 Respiratory Distress Syndrome ........................................................................................................... 225 Meconium Aspiration ......................................................................................................................... 225 Diaphragmatic Hernia ......................................................................................................................... 226 GI and Liver Disorders in the Newborn ............................................................................................... 226 Jaundice in the Neonate ..................................................................................................................... 226 TORCH Infections ................................................................................................................................ 227 Maternal Drug Abuse .......................................................................................................................... 228 Genetic Disorders ............................................................................................................................... 228 Growth, Development, and Nutrition ................................................................................................. 229 Behavioral Disorders ........................................................................................................................... 230 Enuresis........................................................................................................................................... 230 Encopresis ....................................................................................................................................... 230 ADHD .............................................................................................................................................. 230 Child Abuse ..................................................................................................................................... 231 Respiratory Diseases ........................................................................................................................... 231 Small Airway Inflammation ................................................................................................................. 232 Bronchiolitis .................................................................................................................................... 232 Pneumonia ...................................................................................................................................... 232 Cystic Fibrosis.................................................................................................................................. 233 Congenital Heart Disease (CHD) ...................................................................................................... 233 Hypertension .................................................................................................................................. 234 GI Diseases in Children ........................................................................................................................ 234 Diarrhea .......................................................................................................................................... 234 Malabsorption ................................................................................................................................ 235

Celiac Disease ................................................................................................................................. 235 GERD ............................................................................................................................................... 235 Pyloric Stenosis ............................................................................................................................... 235 Malrotation and Volvulus................................................................................................................ 235 Meckel Diverticulum ....................................................................................................................... 235 Intussusception ............................................................................................................................... 236 Esophageal Atresia .......................................................................................................................... 236 Renal and Urologic Diseases in Children ............................................................................................. 236 UTIs in Children ............................................................................................................................... 236 Hematuria ....................................................................................................................................... 236 Henoch Schönlein Purpura (HSP) .................................................................................................... 237 Polycystic Kidney Disease................................................................................................................ 237 Nephrotic Syndrome ....................................................................................................................... 237 Congenital Adrenal Hyperplasia (CAH) ............................................................................................ 237 Anemia ............................................................................................................................................ 237 Sickle Cell Disease ........................................................................................................................... 238 Hemorrhagic Diseases ..................................................................................................................... 238 Seizures ........................................................................................................................................... 239 Fever without a Focus ..................................................................................................................... 239 Neonatal Sepsis ............................................................................................................................... 239 Key Takeaways .................................................................................................................................... 239 Quiz ..................................................................................................................................................... 239 Chapter 17: Obstetrics.................................................................................................................... 246 Care of the Uncomplicated Pregnancy ................................................................................................ 246 First Trimester Screening Tests ........................................................................................................... 246 Second Trimester Screening ............................................................................................................... 247 Third Trimester Screening ................................................................................................................... 247 Advanced Maternal Age ...................................................................................................................... 248 Third Trimester Bleeding..................................................................................................................... 248 Abruptio Placentae ............................................................................................................................. 249 Placenta Previa ................................................................................................................................... 249 Placenta Accreta ................................................................................................................................. 250 Vasa Previa.......................................................................................................................................... 250

Uterine Rupture .................................................................................................................................. 250 GBS (Group B Beta-hemolytic Streptococcus)..................................................................................... 250 Toxoplasmosis..................................................................................................................................... 251 Varicella Infection ............................................................................................................................... 251 Rubella in Pregnancy ........................................................................................................................... 251 Cytomegalovirus (CMV) ...................................................................................................................... 252 Herpes Simplex Virus .......................................................................................................................... 252 HIV Disease ......................................................................................................................................... 252 Syphilis ................................................................................................................................................ 253 Hepatitis B Virus (HBV) ....................................................................................................................... 253 Zika Virus ............................................................................................................................................ 253 Hypertension in Pregnancy ................................................................................................................. 253 HELLP Syndrome ................................................................................................................................. 254 Medical Issues in Pregnancy ............................................................................................................... 255 Cardiac Problems in Pregnancy ....................................................................................................... 255 Thyroid Disorders in Pregnancy ...................................................................................................... 255 Diabetes in Pregnancy..................................................................................................................... 256 UTIs and Bacteriuria in Pregnancy .................................................................................................. 256 Termination of Pregnancy ............................................................................................................... 256 Ectopic Pregnancy ........................................................................................................................... 257 Cervical Incompetence .................................................................................................................... 257 IUGR ................................................................................................................................................ 258 Fetal Macrosomia ........................................................................................................................... 258 Rupture of Membranes before Labor ............................................................................................. 258 Stages of Labor................................................................................................................................ 258 Umbilical Cord Prolapse .................................................................................................................. 259 FHR Tracings.................................................................................................................................... 259 Cesarean Birth................................................................................................................................. 259 Postpartum Hemorrhage ................................................................................................................ 260 Key Takeaways .................................................................................................................................... 260 Quiz ..................................................................................................................................................... 260 Chapter 18: Gynecology ................................................................................................................. 266 Nipple Discharge ................................................................................................................................. 266

Breast Mass ........................................................................................................................................ 266 Breast Cancer ...................................................................................................................................... 267 Uterine Enlargement........................................................................................................................... 268 Postmenopausal Vaginal Bleeding ...................................................................................................... 268 Ovarian Diseases ................................................................................................................................. 269 Cervical Disorders ............................................................................................................................... 269 Causes of Pelvic Pain ........................................................................................................................... 270 Dysmenorrhea .................................................................................................................................... 271 Vaginal Bleeding Disorders ................................................................................................................. 271 Primary Amenorrhea .......................................................................................................................... 272 Secondary Amenorrhea ...................................................................................................................... 272 Premenstrual Syndrome ..................................................................................................................... 273 Endocrine Disorders ............................................................................................................................ 273 PCOS ................................................................................................................................................... 273 Menopausal Disorders ........................................................................................................................ 274 Contraception ..................................................................................................................................... 274 Infertility ............................................................................................................................................. 275 Gestational Trophoblastic Disease ...................................................................................................... 275 Key Takeaways .................................................................................................................................... 276 Quiz ..................................................................................................................................................... 276 Chapter 19: Radiology .................................................................................................................... 282 When to order a CT Scan .................................................................................................................... 282 When to order an MRI Scan ................................................................................................................ 282 When to order a Nuclear Scan ............................................................................................................ 282 When to order an Ultrasound ............................................................................................................. 283 Images you should Recognize on the Test .......................................................................................... 283 Other Radiologic Pearls ....................................................................................................................... 284 Key Takeaways .................................................................................................................................... 284 Quiz ..................................................................................................................................................... 285 Chapter 20: Psychiatry ................................................................................................................... 290 Psychotic Disorders ............................................................................................................................. 290 Antipsychotic Drugs ............................................................................................................................ 290 Anxiety Disorders ................................................................................................................................ 291

Anxiolytic Medications ........................................................................................................................ 291 Obsessive Compulsive Disorder .......................................................................................................... 292 Acute Stress Disorder and PTSD .......................................................................................................... 292 Major Depressive Disorder ................................................................................................................. 292 Bipolar Disorder .................................................................................................................................. 292 Postpartum Depression ...................................................................................................................... 293 ECT (Electroconvulsive Therapy) ......................................................................................................... 293 Antidepressants and Mood Stabilizers ................................................................................................ 293 Somatic Disorders ............................................................................................................................... 294 Eating Disorders .................................................................................................................................. 295 Impulse Control Disorders .................................................................................................................. 295 Personality disorders .......................................................................................................................... 296 Substance Use Disorders..................................................................................................................... 296 Sexual Disorders ................................................................................................................................. 297 Gender Dysphoria Disorder ................................................................................................................ 297 Key Takeaways .................................................................................................................................... 298 Quiz ..................................................................................................................................................... 298 Chapter 21: Emergency Medicine/Toxicology.................................................................................. 304 Trauma Care Basics ............................................................................................................................. 304 Abdominal Trauma ............................................................................................................................. 304 Vasomotor Shock ................................................................................................................................ 305 Head Trauma ...................................................................................................................................... 305 Treatment of Overdoses ..................................................................................................................... 306 Acetaminophen Overdose .................................................................................................................. 306 Aspirin Overdose................................................................................................................................. 307 Benzodiazepine Overdose................................................................................................................... 307 Carbon Monoxide ............................................................................................................................... 307 Digoxin Toxicity ................................................................................................................................... 307 Ethylene Glycol and Methanol Toxicity ............................................................................................... 307 Methemoglobinemia .......................................................................................................................... 308 Neuroleptic Malignant Syndrome ....................................................................................................... 308 Opiate Intoxication ............................................................................................................................. 308 Organophosphates.............................................................................................................................. 308

Arachnid Bites ..................................................................................................................................... 308 Rabies ................................................................................................................................................. 309 Burns ................................................................................................................................................... 309 Acute Altitude Sickness ....................................................................................................................... 309 Glaucoma ............................................................................................................................................ 309 Retinal Detachment ............................................................................................................................ 309 The Red Eye ........................................................................................................................................ 310 Key Takeaways .................................................................................................................................... 310 Quiz ..................................................................................................................................................... 310 Chapter 22: Ethics .......................................................................................................................... 316 Autonomy ........................................................................................................................................... 316 Capacity .............................................................................................................................................. 316 Minors................................................................................................................................................. 316 Informed Consent ............................................................................................................................... 316 Confidentiality .................................................................................................................................... 317 End of Life Issues................................................................................................................................. 317 Reproductive Issues ............................................................................................................................ 318 HIV Disease ......................................................................................................................................... 318 Doctor-Patient Relationship ................................................................................................................ 319 Impaired Physicians ............................................................................................................................ 319 Key Takeaways .................................................................................................................................... 319 Quiz ..................................................................................................................................................... 320 Chapter 23: Biostatistics and Epidemiology ..................................................................................... 326 Descriptive Statistics ........................................................................................................................... 326 Types of Data ...................................................................................................................................... 326 Incidence and Prevalence ................................................................................................................... 327 Precision, Accuracy, and Reliability ..................................................................................................... 327 Standard Deviation ............................................................................................................................. 327 Standard Error of the Mean ................................................................................................................ 327 Z Score ................................................................................................................................................ 328 Confidence Interval ............................................................................................................................. 328 Assessing Data for more than One Group ........................................................................................... 328 T-Score or T-Test and ANOVA ............................................................................................................. 328

Chi-Square Test ................................................................................................................................... 328 Study Designs ...................................................................................................................................... 328 Null Hypothesis and P-Value ............................................................................................................... 329 Type I Error and Type II Error .............................................................................................................. 329 Sensitivity and Specificity .................................................................................................................... 329 Key Takeaways .................................................................................................................................... 330 Quiz ..................................................................................................................................................... 330 Summary ....................................................................................................................................... 335 Course Questions and Answers ...................................................................................................... 339

Preface If you are taking this course, it means you are preparing to take the final USLME test—the USMLE III examination. This is designed to provide you with the information necessary to make clinical decisions in real-world settings. The topics include the various internal medicine subjects (like infectious disease, pulmonology, cardiology, and gastroenterology). It also includes obstetrics and gynecology, radiology, emergency medicine, and ethics, among others.

Regardless of your final specialty, you need to be able to respond effectively in a variety of clinical settings—each of which is covered as part of this course. Study the course material and take the quiz at the end of each chapter. There will be a follow-up test and the end of the course that will mimic the actual test you will take for the USLME III examination.

Chapter one in the course covers infectious disease. While infectious disease is a broad category, there are certain infections that bear studying. The first is sepsis, which is an extreme reaction to a systemic infection. Osteomyelitis is an extreme infection that requires intensive diagnosis and long-term management. The various head and neck, skin, and urinary tract infections are covered as well as STDs and HIV/AIDs. The topic of chapter two in the course is allergy and immunology. The important things to remember for the test include anaphylaxis, a serious and sometimes catastrophic, allergic reaction that often presents to the ED. Office visits related to allergy and immunology include allergic rhinitis and atopic dermatitis—two aspects of the allergic triad. Rarer diseases include primary immunodeficiency states, which will be covered in this chapter.

Chapter three has a focus on tropical, fungal, and animal-borne diseases. These are diseases that sometimes have a vector, which can be an animal or insect. Fungal diseases often affect the lungs but can involve other body areas. Tropical diseases are rare in the US but include Dengue fever, Leishmaniasis, Ebola, and Zika virus. Many of these tropical infections have an animal or insect vector.

The focus of chapter four in the course is cardiology. This includes a range of things, including the management of acute and chronic ischemic heart disease. Congestive heart failure, including pulmonary edema, are discussed. Aspects of valvular heart disease are covered as well as cardiomyopathy and pericardial diseases. Finally, different arrhythmias and treatment strategies are discussed.

Chapter five is about endocrinology. The largest focus is on diabetes mellitus and its complications, including diabetic ketoacidosis, neuropathy, gastroparesis, kidney damage, and retinopathy. Thyroid disease, particularly hypothyroidism and hyperthyroidism, are covered in this chapter, as well as parathyroid diseases. Prolactinomas are discussed (in both men and women) and diseases of the sexual hormones are discussed.

Pulmonology is the subject of chapter six in the course. It includes a discussion of the most common pulmonary conditions, such as asthma and COPD/emphysema, with an emphasis on diagnostics and treatment. Less common lung diseases, such as ARDS, sarcoidosis, pulmonary embolism, and interstitial lung disease are covered. Sleep apnea falls under the main category of pulmonology as is the topic of pneumonia. Finally, rarer diseases like pulmonary aspergillosis and tuberculosis are discussed in this chapter.

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Chapter seven in the course covers joint diseases and related rheumatological diseases. This primarily involves things like rheumatoid arthritis and osteoarthritis but includes the autoimmune diseases related to the joints, like scleroderma and Sjogren’s syndrome. Gout and pseudogout are covered as part of this chapter as well as septic arthritis. There are a great many rarer rheumatologic diseases that are important to know about and are covered in the chapter.

The topic of chapter eight in the course is the study of blood or hematology. This involves an extensive discussion of the different types of anemia and their causes. Sickle cell anemia and sickle cell disease is covered in this chapter. Several rare blood disorders are covered as well as leukemia, which is more common. The test will also cover platelet cell disorders so this is a part of the chapter as well, including disorders involving too few or too many platelets (thrombocytopenia and thrombocytosis).

Chapter nine in the course covers the topic of gastroenterology. It includes a discussion of esophageal disorders, including dysmotility and esophageal cancer, stomach and small intestinal diseases, peptic acid disease, malabsorption, constipation, diarrhea, and colon cancer. Hepatitis and other hepatic diseases are also covered as part of this chapter on GI-related disorders.

Neurology is the topic of chapter ten. It starts with a discussion of strokes and TIAs, the most common neurologic problems. Seizures, Parkinson’s disease, multiple sclerosis, and dementia are also covered.

Headache, CNS infections, and hemorrhages in the CNS are discussed as part of a thorough discussion of neurologic problems seen by neurologists and non-neurologists alike. The goal is to have a broad understanding of common neurological conditions, the diagnostics involved, and their treatment.

Chapter eleven in the course covers the topic of nephrology. The chapter covers acute and chronic renal failure and their causes as well as the different inflammatory renal diseases, such as interstitial nephritis and glomerulonephritis. The different electrolyte disorders associated with renal insufficiency and renal diseases are discussed in the chapter. Primary and secondary hypertension, which is often related to the kidneys is part of the chapter’s discussion.

Chapter twelve in the course is, by necessity, a brief one, as the USMLE III test does not ask many questions about oncology. The main focus of the test is on screening for the various cancers. Only a few cancers are currently screened for in clinical practice, including breast cancer, cervical cancer, prostate cancer, skin cancer, and colon cancer. The USMLE III test focuses on currently accepted guidelines and avoids the gray areas that exist in detecting some forms of cancer.

Chapter thirteen is a short assessment of preventive medicine. This involves cancer screening and other types of screening tests performed on asymptomatic patients. Other preventive strategies include immunizations given to adults and children. There are other screening tools in the chapter that will be discussed. This is a brief chapter that covers what you’ll need to learn for the examination.

The focus of chapter fourteen in the course is dermatology. This will include a discussion of the various types and classifications of dermatologic conditions, including bullous diseases of the skin, skin infections, sexually transmitted diseases that affect the skin, scabies and related diseases, malignancies, toxin-mediated diseases, eczematous diseases, acne, and rosacea.

Chapter fifteen is about surgery, which is a broad topic. It starts with a discussion of general surgical topics, which mostly encompass the abdomen and abdominal surgery. Preoperative and postoperative care are a part of this discussion. Orthopedic surgery topics are also covered and issues regarding 2

urology and its surgical management are discussed. Finally, vascular surgery is covered to complete this chapter.

Chapter sixteen in the course encompasses the topic of pediatrics. The first part of the chapter covers newborn care and diseases of the neonate, including common genetic diseases. Then comes a discussion of childhood growth and development, including nutrition. Common behavioral disorders in pediatrics are discussed. Respiratory/cardiac conditions are covered in detail. Childhood GI and renal/gastrointestinal disorders are a part of this chapter. Endocrine, hematologic, and neurologic diseases as they apply to children are discussed as are childhood infectious diseases.

Chapter seventeen talks about obstetric care of the normal and complicated pregnancy. The first, second, and third trimester normal pregnancy care is discussed as are complications of these aspects of pregnancy. Prenatal and perinatal infectious diseases are covered in detail. The management of hypertensive disorders in pregnancy are part of this chapter. Medical issues complicating a pregnancy are discussed as well. Finally, there is a discussion of normal and abnormal labor as well as postpartum care.

The topic of chapter eighteen in the course is gynecology. It starts with a discussion of breast diseases, both benign and malignant. Uterine diseases are next, focused on signs of uterine disease and their workup. The same is true of ovarian diseases, cervical diseases, and pelvic pain. Disorders of vaginal bleeding and menstruation are covered. There are endocrine diseases that primarily affect the woman’s reproductive tract, which are discussed, as are menopausal diseases. Contraception and infertility are briefly discussed.

As radiology is not tested much on the USMLE III course, chapter nineteen in the course is brief. It will discuss the test specifically, including when a certain test is indicated or not in radiologic evaluations.

There will be a list of things you will need to memorize regarding radiology for the test and some radiologic terms to memorize.

Chapter twenty focuses on different psychiatric disorders. There is a section on psychotic disorders and their treatment, a section on anxiety disorders and trauma-related disorders. Mood disorders like bipolar disorder and major depression are discussed as is the treatment of these disorders. Somatic symptoms and somatoform disorders are covered. Eating disorders are a part of this chapter as are impulse-control disorders. Substance use disorders and substance withdrawal are covered in detail in this chapter as well. Finally, sexual disorders are covered.

Chapter twenty-one in the course involves those things that an emergency medicine physician might encounter in the ED. It starts with a discussion of trauma and shock management as well as head trauma. Management of the overdose patient is part of the chapter as are several toxicological emergencies that usually present to the ED for initial management.

Chapter twenty-two is a very brief chapter on medical ethics. It includes issues like autonomy, capacity, and the care of minor patients. Informed consent Is covered as is confidentiality. Finally, end-of-life issues are discussed along with the doctor-patient relationship and what to do with an impaired physician.

Chapter twenty-three in the course is a discussion on epidemiology and biostatistics. It will cover the basic types of research data, incidence and prevalence, precision, accuracy, and standard deviation.

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Research concepts of the Z-score and confidence intervals are covered. Different types of study designs are explained in this chapter as well as the terminology associated with them. The meaning of the Pvalue is explained. The common terms of specificity, sensitivity, and the positive and negative predictive values are discussed as part of this chapter.

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Chapter 1: Infectious diseases This chapter covers infectious disease. While infectious disease is a broad category, there are certain infections that bear studying. The first is sepsis, which is an extreme reaction to a systemic infection.

Osteomyelitis is an extreme infection that requires intensive diagnosis and long-term management. The various head and neck, skin, and urinary tract infections are covered as well as STDs and HIV/AIDs.

Sepsis Sepsis is an extreme bodily response to an infection that becomes life-threatening because of hypotension that leads to hypotension, tissue damage, organ failure, and ultimately, to death. The infection is triggered by an infection elsewhere in the body. The four infections most linked to sepsis include pneumonia, urinary tract infection (most common source in the elderly), skin infections, and GI infections. The most common organisms isolated in sepsis include Staphylococcus aureus, E. coli, and certain strains of Streptococcus.

At risk patients include adults 65 years or older, those with chronic disease (diabetes, kidney failure, cancer, malnutrition, and lung disease), the immunosuppressed, and infants under one year of age.

Symptoms to look out for include dyspnea, delirium, tachycardia, fever or hypothermia with cold, clammy skin, and extreme pain. The diagnosis is clinical and includes a culture of all catheter tips (urinary and IV catheters, as these will give the best yield), sputum cultures, urine cultures, and blood cultures. Immediate parenteral antibiotics are crucial as delays increase the risk of death by 8 percent per hour. Oxygen, IV fluids, vasopressors, and dialysis are common treatments after the institution of antibiotic therapy.

Osteomyelitis Osteomyelitis, infection of the bone, often occurs in high-risk situations, such as diabetes, severe trauma to the area, previous splenectomy, IV drug use, previous orthopedic surgery, and peripheral arterial disease (PAD). It often starts as an ulcer or soft tissue infection that spreads directly to bone. It must be suspected when there is a skin ulceration, particularly in diabetics and those with PAD. The goal of the evaluation is to distinguish between skin ulcerations and contiguous spread to bone.

The initial test of choice is the plain x-ray of the bone. If this is negative but the clinical suspicion is high, an MRI of the bone is the next step. The most accurate test (and one that will guide treatment) is the bone biopsy with culture of the suspicious area. Even though it can take up to 2 weeks for the plain x-ray to become positive, the plain film is still the test of choice. The earliest sign of osteomyelitis on x-ray is elevation of the periosteum at the site of the infection.

Causative organisms vary with age: • •

Infants at 0-4 months of age: S. aureus, Enterobacter sp., Group A and Group B Streptococcus Children aged 4 months to 4 years: S. aureus, Group A Streptococcus, Haemophilus influenzae, and Enterobacter sp.

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• • •

Children and adolescents: S. aureus, Enterobacter, Group A Streptococcus sp., or H. influenzae Adults: S. aureus and rarely Enterobacter and Streptococcus sp.

Sickle cell anemia patients: Salmonella sp.

Figure 1 is an x-ray image involving osteomyelitis of the calcaneus:

Figure 1 The most common method of spread of infection to bone is contiguous spread, followed by hematogenous spread, penetrating trauma, and iatrogenic causes (internal fixation of fractures and joint replacements). Because hematogenous spread is possible, a blood culture should also be done. The best way to monitor treatment is to follow the erythrocyte sedimentation rate (ESR). A swab of the ulcer is highly inaccurate. The bone scan and the MRI are equally sensitive for excluding osteomyelitis but the MRI is more specific so it is the preferred test.

If the ESR is still elevated after 4-6 weeks of an appropriate antibiotic, then surgical debridement should be considered. The single-most organism to cover for is S. aureus with oxacillin or nafcillin IV for 4-6 weeks (if sensitive). If MRSA is isolated, the treatment is vancomycin, dalbavancin, oritavancin, daptomycin, ceftaroline, or linezolid. Oral therapy is never recommended for S. aureus osteomyelitis. If the disease is chronic, it needs debridement. The patient may need a PICC line or central line for longterm antibiotic use. Amputation is necessary for the most severe cases.

If the organism is Salmonella or Pseudomonas (or another gram-negative bacillus), the treatment of choice would be to treat with a culture-sensitive antibiotic. There is no need to treat chronic osteomyelitis. A biopsy can be obtained and cultured before starting the culture-sensitive antibiotic.

Head and Neck Infections There are a number of head and neck infections seen in a typical outpatient or ED setting. Most are obvious and easily treated.

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Otitis Externa The main symptoms are itching, pain, and drainage from the external auditory canal. It is essentially the same thing as cellulitis of the skin of the external auditory canal. There will be increased pain on manipulation of the tragus and difficulty seeing the external auditory canal because of swelling of the tissues. It is typically linked to swimming because swimming washes out the acid environment of the canal. Foreign objects (like cotton swabs and hearing aids) can contribute to otitis externa.

This is a clinical diagnosis with no routine cultures necessary. The treatment is topical antibiotics. The most commonly used and effective antibiotics are ofloxacin, polymyxin/neomycin, and ciprofloxacin.

Topical hydrocortisone can be added to decrease itching and swelling. Acetic acid mixed with water will restore the acidic environment of the external auditory meatus. Tell the patient that acidic cerumen (earwax) is protective so not to use cotton swabs too much. A common organism in external otitis is Pseudomonas aeruginosa, followed by Staphylococcus aureus.

Cerumen impaction can complicate treatment. If seen on exam, attempt to flush it out with saline under pressure, use mineral oil, use hydrogen peroxide, or use carbamide peroxide to get rid of the impaction. Direct mechanical removal with a curette after softening the wax with mineral oil is the most effective way of removing it.

Patients can have malignant external otitis, which represents osteomyelitis of the skull from Pseudomonas. It is often seen in diabetics. It can lead to brain abscess if not adequately treated. MRI and bone biopsy can diagnose this disorder. Best original test is CT or MRI of the skull; however, the most specific test is the bone biopsy. Treatment includes surgical debridement and anti-Pseudomonas drugs (ciprofloxacin, cefepime, piperacillin, aztreonam, or carbapenem.

Otitis Media This is characterized by a tympanic membrane that is bulging, red, dull, and immobile. There may be decreased hearing in the affected ear. As immobility is the most sensitive indicator of otitis media, insufflation should be done. If mobility is noted, there is no otitis media. There is no other diagnostic test that needs to be done. The Tympanocentesis with culture is the most specific test but it is rarely necessary.

The best initial therapy is amoxicillin for 7-10 days. If this does not improve the symptoms after three days, switch to one of the following: amoxicillin/clavulanate, cefpodoxime, cefprozil, cefuroxime, ceftibuten, or cefdinir. The three most common causative agents include Haemophilus, Pneumococcus, and Moraxella. Getting the Haemophilus influenzae shot does not protect against this.

Sinusitis This is a patient with purulent nasal discharge, facial tenderness, tooth pain, fever, headache, and a bad taste in their mouth. The sinuses will have decreased transillumination. Most are viral; however, bacterial causes include Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis.

The best initial test is the CT scan of the sinuses, while the most accurate test is a sinus aspirate culture.

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The treatment is nearly identical to that of otitis media with the addition of inhaled corticosteroids. If there is seven days of decongestants, purulent discharge, fever, and pain, the first-line agent is amoxicillin-clavulanate for 10 days.

Pharyngitis The diagnosis clinical, based on a history of throat pain, exudate, adenopathy, and a lack of hoarseness/cough. The best initial test is the rapid strep test, with a positive test just as specific as a culture. If the rapid strep test is negative in adults, no further evaluation is necessary. In children, a negative test should be followed up with a culture, which is the most accurate test. The treatment is Pen VK or amoxicillin. If penicillin-allergic, give azithromycin, clarithromycin, or cephalexin (if only a rash is seen with penicillin).

Influenza This is a patient with fever, headache, sore throat, cough, myalgias/arthralgias, and fatigue. Influenza can be diagnosed clinically or with a viral rapid antigen detection of a nasal pharyngeal swab. The main treatment is oseltamivir or zanamivir if presentation is within 48 hours of onset of symptoms. These antivirals will work against both influenza A and influenza B. Amantadine and rimantadine are wrong answers as they only cover against influenza A. Peramivir is also a wrong answer in an ambulatory patient as it is intravenous and reserved for hospitalized patients.

As for vaccination, it is not contraindicated in egg allergies and everyone six months of age or older should take it. It is particularly indicated in patients with CHF, COPD, healthcare workers, steroid use, or over fifty years of age. The live attenuated intranasal vaccination is only for patients under 50 who do not have any of the special indications.

Skin Infections This section covers skin and nail infections.

Impetigo This is considered the most superficial of all bacterial skin infections. It can be caused by Staphylococcus aureus or Streptococcus pyogenes and involves the epidermis only. The skin will be weepy, crusting, and oozing. This is a clinical diagnosis, particularly with the typical “honey-colored” lesions. The treatment of choice is topical mupirocin or retapamulin. Severe disease involves oral medications, such as dicloxacillin and cephalexin. Community-acquired MRSA (if suspected) should be treated with doxycycline or TMP/SMX. If PCN allergic, use cephalexin (if no anaphylaxis with PCN), clindamycin, doxycycline, linezolid, or TMP/SMX. Severe infections with PCN-anaphylaxis needs treatment with vancomycin, telavancin, linezolid, or daptomycin.

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Erysipelas This is a skin infection caused by Group A streptococcus. The main characteristic is of bright red and hot skin, usually on the lower extremities. The only workup necessary is a blood culture as this may be positive. If obvious, go to treatment strategies, including oral cephalexin or dicloxacillin. Topical antibiotics are not indicated. If confirmed by blood culture to be Group A beta hemolytic strep, pen VK can be used.

Figure 2 demonstrates erysipelas of the lower extremity:

Figure 2

Cellulitis The patient will have cellulitis of any part of the body with the leg and arm most common. If seen on the lower extremity, a Doppler ultrasound must be done to rule out DVT. The two main causes are Streptococcus pyogenes and Staphylococcus aureus. No other workup is necessary. If the disease is minor, treat with oral cephalexin, dicloxacillin, or amoxicillin/clavulanate. If anaphylaxis with PCN, give linezolid, daptomycin, or vancomycin. If minor disease, use clindamycin of TMP/SMX. For severe disease, use oxacillin, nafcillin, cefazolin, or IV ampicillin/sulbactam.

Folliculitis, Carbuncles, and Furuncles These are always from Staphylococcus aureus and start in a hair follicle that becomes infected.

Folliculitis involves the smallest lesions, followed (in order of increasing size) by furuncles, carbuncles, and boils. An abscess would be the largest lesion. The treatment is the same as for cellulitis; however, larger lesions would benefit from incision and drainage.

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Fungal Infections This can involve the skin or nails. In skin infections, there is itching, bald patches, and dandruff of the scalp. In onychomycosis, the nails are brittle, thickened, yellow, and cloudy. The diagnosis involves a KOH smear of the skin or nail scraping. The fungal organisms can be seen on the smear. The topical treatment (if no hair or nail involvement) includes clotrimazole, ketoconazole, econazole, miconazole, terconazole, nystatin, and ciclopirox. Oral medications are used for tinea capitis and onychomycosis (including terbinafine, itraconazole, and griseofulvin (less effective). Liver function studies need to be done every six weeks on terbinafine as it will raise LFTs.

Sexually Transmitted Diseases This section covers the various STDs seen in clinical practice.

Urethritis The key finding is urethral discharge. Symptoms include dysuria, frequency, urgency, and burning of the urethra (but do not have to be present to make the diagnosis). Testing includes a urethral swab, looking for WBCs, Gram-stain, and DNA probe (NAAT testing). The nucleic acid amplification tests (NAATs) are similar to PCR testing and can be done on the urine. Treatment should cover for both gonorrhea and chlamydia (which means two medications). Recurrent episodes of gonorrhea should raise the suspicion for terminal complement deficiency. For nonpregnant patients, provide IM ceftriaxone and either a single dose of azithromycin or a week of doxycycline. Pregnant patients need just ceftriaxone IM and azithromycin.

Cervicitis The key finding is cervical discharge, although there can be other symptoms. The workup is identical to urethritis with a swab of the cervical culture and NAAT testing for gonorrhea and chlamydia. The treatment is the same as for cervicitis.

Pelvic Inflammatory Disease (PID) The classic presentation is abdominal pain, fever, abdominal tenderness, and cervical motion tenderness. Vaginal discharge or dysuria may be present. The CBC with diff will measure severity. A pregnancy test, cervical culture, and NAAT for gonorrhea and chlamydia should be done. A laparoscopy is very specific but almost always unnecessary unless there is treatment failure. Treatment includes IM ceftriaxone and doxycycline (if not pregnant). Penicillin-allergic patients should have gentamycin and clindamycin, while inpatients can be treated with IV cefoxitin and doxycycline. Safe antibiotics in pregnancy include penicillin, cephalosporins, aztreonam, azithromycin, and erythromycin.

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Epididymitis and Orchitis The testicle is in its normal position but it is extremely painful and tender to the touch. The treatment of choice is ceftriaxone and doxycycline for those under 35 years of age as this may be an STD with either gonorrhea or chlamydia. For men over 35 years, the first-line treatment is a fluoroquinolone antibiotic.

No immediate evaluation needs to be done other than to treat based on clinical findings.

Ulcerative Genital Diseases These are ulcerative lesions with localized lymphadenopathy. There are several kinds of diseases labeled under this category, including the following: •

•

•

Chancroid—this is a painful ulceration from Haemophilus ducreyi. The test of choice is a gram stain looking for gram-negative coccobacilli and special culture for this organism. The treatment is a single IM injection of ceftriaxone and a single dose of azithromycin.

Lymphogranuloma venereum—the key feature is large “buboes” or tender lymph nodes in the groin that may open up sinus tracts. The test is serology on the ulcers for Chlamydia. Treatment is doxycycline or azithromycin plus aspiration of buboes.

Herpes simplex (Genital Herpes)—the general evaluation is the PCR test for herpes, which is more sensitive than a viral culture but doesn’t give sensitivities. A workup isn’t necessary when the clinical diagnosis is obvious. Chronic infections are treated with suppressive therapy with acyclovir or valalcyclovir (only acyclovir in pregnancy). If there is resistance, treat with foscarnet (not ganciclovir as there will be resistance to that as well).

Syphilis This is a complex infectious process stemming from Treponema pallidum. It starts with a chancre and adenopathy for which a darkfield test is done (followed by a VDRL or RPR, which are only 75 percent sensitive in primary syphilis). The treatment of primary syphilis is an injection of penicillin or doxycycline for patients who are penicillin-allergic.

A Jarisch-Herxheimer reaction is possible from pyrogens released from the dying organisms, leading to fever, headache, and myalgias. This is self-limited.

Secondary syphilis involves alopecia areata, rash, condylomata lata, and mucous patches. The RPR and FTA are 100 percent sensitive at this point. The treatment is the same as for primary syphilis.

Tertiary or neurosyphilis involves general paresis, tabes dorsalis, and an Argyll-Robertson pupil. The RPR is only 75 percent sensitive. The FTA is 100 percent sensitive in the CSF and 95 percent sensitive in the serum. The CSF VDRL is only 50 percent sensitive in the CSF. Treatment is always with IV penicillin with desensitization done in PCN-allergic patients.

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Figure 3 demonstrates secondary syphilis:

Figure 3

Genital Warts Regardless of what they are called (verrucous wart, molluscum contagiosum, or condylomata acuminata), they are all caused by the human papilloma virus. The only treatment available for these is mechanical destruction of the lesions. Imiquimod will stimulate the immune system to slough off the warts. There are many types of destructive methods, from surgical resection to trichloroacetic acid.

Urinary Tract Infections Urinary tract infections include cystitis and acute pyelonephritis.

Cystitis The presentation is usually urinary frequency, urgency, dysuria, and burning. The best initial test is the urinalysis; however, the most accurate test is the urine culture. Uncomplicated cystitis cases where there is little E. coli resistance can be treated with nitrofurantoin or fosfomycin for three days. High resistance areas (greater than 20 percent) require treatment with ciprofloxacin or levofloxacin.

Nitrofurantoin and fosfomycin can be used together in pregnancy and can be used in high-resistance areas. Complicated cystitis, in which there is obstruction, tumor, stricture, stone, or anatomic abnormality, should be treated for 7 days with TMP/SMX or ciprofloxacin.

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Acute Pyelonephritis The patient will present with all of the typical UTI symptoms plus flank pain, fever, and flank tenderness.

This type of individual is sicker than those with cystitis. The typical outpatient treatment is ciprofloxacin but anything that covers for gram-negative bacilli can be used for inpatients. If this is not a recurrent infection and there is no evidence of a stone or other urinary tract abnormality, no imaging needs to be done.

A complication of pyelonephritis is a perinephric abscess. The patient will have classic pyelonephritis symptoms but will not respond within 5-7 days to treatment. An ultrasound of the kidneys is the test of choice with surgical drainage of the abscess sometimes necessary. The treatment is a fluoroquinolone plus oxacillin, vancomycin, or nafcillin for staphylococcus coverage because quinolones alone will result in overgrowth of staphylococcus.

Prostatitis This is seen in males who complain of frequency, dysuria, urgency, and pain in the perineum or sacral area. The prostate will be tender. The best initial test is the urinalysis followed by prostate massage and urine WBC evaluation after that. The treatment is TMP/SMX or a quinolone antibiotic. Patients with acute disease should be treated for 2 weeks, while patients with chronic infections need 6 weeks of treatment.

HIV/AIDS Things to know include when to treat: • • • • •

At any CD4+ count of less than 500 All symptomatic patients regardless of CD4 count or viral load All pregnant women, regardless of labs Needle-stick situation when the patient is known to be HIV positive Any time the viral load is detected, regardless of CD4+ count (strong recommendation)

HAART (highly active anti-retroviral therapy) includes any of the following: • • •

Lamivudine plus abacavir plus dolutegravir (an integrase inhibitor) Tenofovir and emtricitabine plus an integrase inhibitor Tenofovir and emtricitabine plus atazanavir or darunavir

The three main integrase inhibitors are dolutegravir, elvitegravir, and raltegravir. These are used with two nucleosides (tenofovir and emtricitabine). The side effect profile is worth remembering. For example, tenofovir will cause renal tubular acidosis, decreased bone density, and Fanconi syndrome.

Abacavir is only indicated in HLA B*5701 patients.

As a class, the nucleoside reverse transcriptase inhibitors cause lactic acidosis; the protease inhibitors cause hyperglycemia and hyperlipidemia. Nonnucleoside reverse transcriptase inhibitors cause drowsiness and mental health issues. Integrase inhibitors do not cause many side effects. The standard 13

of care is two nucleosides and an integrase inhibitor. Test the HLA type of the patient before starting abacavir.

PrEP or preexposure prophylaxis is given to high-risk patients who have known HIV-positive sexual encounters or who share needles. They take tenofovir and emtricitabine prior to exposure, continued for 30 days after last exposure. Tenofovir has the advantage of treating hepatitis B. Postexposure prophylaxis is given after an HIV-contaminated needlestick. The patient receives full HAART for a month. Abacavir cannot be used because it would take too long to have the HLA type return. Two nucleoside reverse transcriptase inhibitors and an integrase inhibitor are recommended.

In pregnancy, two nucleoside reverse transcriptase inhibitors and a protease inhibitor are recommended. These will reduce the chances of maternal-fetal transmission to less than 1 percent and should be used on all women who are pregnant and HIV positive, regardless of other labs or trimester of pregnancy.

Patients with less than 200 CD4+ cells need TMP/SMX or atovaquone or dapsone if allergic to sulfa drugs as prevention against pneumocystis pneumonia. Pentamidine was once used but has a poor efficacy when aerosolized and given to these patients. If the CD4+ count is less than 50 CD4+ cells, they need prophylaxis also against Mycobacterium Avium-Intracellulare.

Opportunistic Infections Patients who fail pneumocystis prophylaxis may develop the disease and will have dry cough, hypoxia, dyspnea, and an elevated LDH level. The best test is a CXR but the most accurate is a bronchoalveolar lavage. Treatment is with IV TMP/SMX, IV pentamidine, atovaquone (if mild), IV clindamycin/primaquine. Dapsone is only used for prevention. IV steroids will help if severe.

Toxoplasmosis presents with headache, nausea, vomiting, and some focal neurologic signs. There will be a contrast-enhancing lesion on CT of the head. Treatment is with pyrimethamine and sulfadiazine for 2 weeks before repeating the CT with contrast. If not shrinking, perform a brain biopsy.

Cytomegalovirus can be seen with CD4+ counts of less than 50 cells/microliter. The patient will have blurry vision with the diagnosis based on an ophthalmoscope evaluation. There will be lesions on exam.

The treatment of choice is IV ganciclovir and foscarnet with oral valganciclovir until the CD4+ count rises.

Cryptococcus can be seen wit CD4+ cells less than 50, along with fever and headache. A lumbar puncture is the test of choice, showing lymphocytosis in the CSF. The most accurate test is the cryptococcal antigen test (95 percent accurate and sensitive). Treatment is with amphotericin B and 5-FC, followed by fluconazole. The fluconazole is given until the CD4+ count rises. When and if this happens, only the retroviral therapy needs to be given.

Progressive focal leukoencephalopathy (PML) can be seen with a CD4+ count of less than 50. It can be tested for with a CT or MRI of the brain. There is no ring enhancement of the brain lesions. The PCR evaluation for the JC virus is most accurate. There is no treatment except to give HAART to bring up the CD4+ count.

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Mycobacterium Avium-Intracellulare (MAI) will be seen with PCR counts less than 50. There will be weight loss, fatigue, anemia, and fever. The bone marrow will be involved with an increased alkaline phosphatase. The best tests include the liver biopsy or bone marrow biopsy. A blood culture is not very sensitive. It is treated with azithromycin, rifampin, and ethambutol. Prevention is with azithromycin or clarithromycin.

Infective Endocarditis The diagnosis is made by satisfying the Duke criteria (two major and minor criteria). The major criteria include a positive blood culture for Strep viridans, Staph aureus, Strep epidermidis, Enterococci, gramnegative rods, or candida, and having an abnormal echocardiogram suggestive of endocarditis. Minor criteria include fever, risk factors, new murmur, vascular abnormalities (e.g., Janeway lesions), and immunological findings (e.g., Osler nodes and Roth spots).

In a patient with fever and new or changing murmur, the next step is to perform two blood cultures. If these are positive, do an echocardiogram. The minor criteria are helpful if the blood cultures are negative. A transthoracic echo is only 60 percent sensitive, yet a TEE (transesophageal echo) is 90-95 percent sensitive and specific for bacterial endocarditis. The most common organisms for culturenegative endocarditis include Bartonella and Coxiella.

The best empiric therapy is vancomycin and either gentamicin or ceftriaxone. This will cover for all major organisms, including MRSA. Treat for 4-6 weeks. If anatomic valvular abnormalities, consider valve surgery as antibiotics alone will not treat the infection.

Preventive measures/prophylaxis is necessary under only these conditions: • • • • • • •

Unrepaired cyanotic heart disease Prosthetic valves Prior endocarditis Transplant patients with valvular disease Dental work likely to cause bleeding (amoxicillin or clindamycin) Respiratory tract surgery Infected skin surgery

It is not recommended for these conditions: • • • • • • • • •

Dental fillings OB/GYN procedures Urinary tract procedures Flexible endoscopy of any kind Aortic stenosis or regurgitation Pacemaker patients Mitral valve prolapse Mitral stenosis or regurgitation IHSS

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The preventatives of choice include amoxicillin, cephalexin, clindamycin, azithromycin, or clarithromycin for dental procedures. Skin procedures require cephalexin or vancomycin (with PCN-anaphylaxis patients).

Key Takeaways • • • •

Pay attention to the sensitivity and specificity of the various tests used to work up infectious diseases as this will dictate which tests are ordered.

In many cases, a biopsy and culture of an infected area of bone, skin, etc., is high specific but rarely need to be performed if clinical suspicion is high.

Patients who are penicillin-allergic with anaphylaxis are treated differently than patients with a rash to penicillin.

The best treatment for most opportunistic infections in HIV disease is to raise the CD4+ count with HAART.

Quiz 1. The patient you are treating is a 76-year-old male with BPH and a chronic indwelling urethral catheter. He presents with fever, hypotension and confusion. What diagnostic test would best guide the treatment strategy? a. CBC with diff b. Blood culture c. Suprapubic catheterization and urinalysis d. Culture of urethral catheter e. Renal and bladder ultrasound Answer: d. The test with the greatest yield would be a culture of the tip of the urethral catheter as this is likely to grow out the organism causing the patient’s sepsis.

2. In treating an 85-year-old female with fever, confusion, and a urinalysis suggestive of a UTI, what organism would you most want to have coverage for? a. Escherichia coli b. Staphylococcus saprophyticus c. Enterococcus d. Streptococcus e. Staphylococcus aureus Answer: a. In the absence of a positive culture, the patient needs empiric coverage. The most common organism in 80-90 percent of urinary tract infections is Escherichia coli. As the patient has symptoms of sepsis, the antibiotics should be parenteral.

3. The patient you are seeing in the ED is a 2-day-old neonate who presents with irritability, lack of eating behaviors, decreased urination, and an exam that is significant for cyanosis of the perioral area and distal extremities. An O2 sat is 85 percent on room air. The exam is unremarkable and

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the Group B strep status of the mother is unknown. What is the priority treatment of choice after evaluating the patient and sending off cultures? a. High-flow oxygen b. Vasopressors c. Parenteral antibiotics d. Intravenous fluid bolus e. Nasogastric tube feedings Answer: c. The infant presents with signs of sepsis. The urgent/priority treatment of choice is to start parenteral antibiotics first and treat other symptoms after the antibiotics have begun.

4. The patient is a 22-year-old male with a traumatic laceration to his anterior calf. He did not have it treated and now the overlying skin is infected. An x-ray shows osteomyelitis of the tibia.

What is the most likely causative organism? a. Staphylococcus aureus b. Haemophilus influenzae c. Salmonella d. Enterobacter e. Pseudomonas Answer: a. By a vast majority, Staphylococcus aureus is the organism isolated in young adults with osteomyelitis and no other risk factors.

5. The 55-year-old diabetic patient has severe left ear pain, itching, and foul-smelling drainage from the external auditory canal. Topical antimicrobials have been tried and have been found to be unsuccessful. What is the initial evaluation of choice? a. External auditory canal culture b. MRI of the ear c. Plain film of the skull d. Bone biopsy e. ESR Answer: b. The MRI of the ear is a good first test for evaluating possible malignant external otitis media.

6. The patient is a 45-year-old diabetic female with evidence of malignant external otitis media.

What would a least likely choice be in antibiotics? a. Ciprofloxacin b. Cefepime c. Piperacillin d. Aztreonam e. Ceftriaxone Answer: e. The choice of antibiotic should cover for Pseudomonas and ceftriaxone has the least ability to cover for this organism. The other antibiotics have good Pseudomonas coverage.

7. The patient is an adult with sore throat, adenopathy, and exudate on the tonsils. The rapid strep test is negative. What is the next clinical step? a. Treat empirically with Pen VK 17

b. Obtain a throat culture c. Obtain a Monospot d. Repeat rapid strep test in 48 hours e. Do not treat or test further Answer: e. In adults, a rapid strep is very sensitive so a negative test excludes streptococcal pharyngitis.

8. The patient is a 14-year-old female with a sore throat and a positive rapid strep test. She has had anaphylaxis with penicillin. What is the antibiotic of choice? a. Ciprofloxacin b. Cephalexin c. Azithromycin d. Clindamycin e. Tetracycline Answer: c. The antibiotic of choice is azithromycin or clarithromycin because of the history of anaphylaxis with penicillin.

9. The patient is ambulatory and has signs and symptoms influenza. They have presented within 48 hours of symptoms. What is the treatment of choice? a. Azithromycin b. Oseltamivir c. Amantadine d. Rimantadine e. Peramivir Answer: b. Both oseltamivir and zanamivir have coverage against influenza A and influenza B. They are the first-line agents for ambulatory patients with influenza. Peramivir is intravenous and both amantadine and rimantadine cover for influenza A only. Azithromycin is not indicated.

10. The patient is a 65-year-old female with a large patch of redness, warmth, and swelling of her lower extremity suggestive of cellulitis. She has no allergies. What is the next evaluation and/or treatment of choice? a. Treat with TMP/SMZ b. Obtain blood culture c. Obtain small skin biopsy for culture d. Treat with dicloxacillin e. Obtain lower extremity Doppler ultrasound Answer: e. The patient with lower extremity cellulitis needs a Doppler ultrasound in order to rule out a deep vein thrombosis.

11. The patient is a 32-year-old sexually active, heterosexual male who has recurrent gonorrhea infections. What should be suspected and tested for? a. Malabsorption of antibiotics d. Steroid use c. Terminal complement deficiency d. HIV/AIDS 18

e. Splenectomy Answer: c. Patients with recurrent gonorrhea infections despite treatment should be evaluated for terminal complement deficiency.

12. The patient has urethritis with classic symptoms. This is a 24-year-old pregnant woman. Besides IM ceftriaxone, what drug should be given? a. Azithromycin b. Doxycycline c. Dicloxacillin d. Ciprofloxacin e. Erythromycin Answer: a. Pregnant patients should have coverage for chlamydia to include ceftriaxone and azithromycin. Doxycycline is contraindicated in pregnancy and the other drugs are not indicated for chlamydia.

13. The patient is a 24-year-old male with multiple clear closed vesicles on the tip of the penis and mild local adenopathy. What is the next step in evaluation and management? a. PCR evaluation b. Viral culture c. Valalcyclovir d. Valganciclovir e. Tzanck smear Answer: c. When the diagnosis is clear, the patient can be treated based on the clinical exam alone. If the lesions ulcerate, a Tzanck prep or PCR test can be done.

14. The patient is a 30-year-old male with a painless firm ulcer on the shaft of the penis and groin adenopathy. The VDRL is obtained and is negative. What is the next management step? a. IM penicillin b. RPR c. FTA d. Repeat VDRL e. Darkfield microscopy Answer: e. The patient can have a better sensitivity in diagnosing syphilis with darkfield microscopy. The RPR and VDRL are only 75 percent sensitive in primary syphilis.

15. An otherwise healthy 25-year-old female presents with classic UTI symptoms. The UA shows 60 WBCs per hpf. What is the next clinical step? a. Obtain a culture and await the results b. Obtain a urine culture and treat with empiric antibiotics c. Treat with TMP/SMX for three days d. Treat with ciprofloxacin for 7 days e. Get an ultrasound of the kidneys and bladder

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Answer: c. This is a healthy young woman with classic UTI symptoms. No urine culture is necessary and, because there is no evidence of this being a complicated UTI, three days of TMP/SMX is sufficient.

16. The patient has HIV disease and is on prophylaxis against pneumocystis pneumonia. He develops a dry cough, dyspnea, and hypoxia. The CXR shows increased interstitial markings.

What treatment for pneumocystis pneumonia is least likely to be used? a. IV pentamidine b. IV Dapsone c. Atovaquone d. IV Clindamycin/primaquine d. IV TMP/SMX Answer: b. Dapsone is not given intravenously and is only used for prevention of pneumocystis pneumonia—not for treatment.

17. What combination of medications are generally used to treat HIV disease in pregnant women? a. Two nucleoside reverse transcriptase inhibitors and a protease inhibitor b. A protease inhibitor and an integrase inhibitor c. A nucleoside inhibitor, a protease inhibitor, and an integrase inhibitor d. Two integrase inhibitors d. Two nucleoside reverse transcriptase inhibitors and a non-nucleoside reverse transcriptase inhibitor Answer: a. In pregnancy, the treatment of choice is two nucleoside reverse transcriptase inhibitors and a protease inhibitor.

18. The patient has HIV disease and a CD4+ count of less than 50. They present with fever, weight loss, fatigue and anemia. What opportunistic infection do you most want to include in the workup? a. Cryptococcus b. Cytomegalovirus c. Toxoplasmosis d. Mycobacterium Avium Intracellulare e. Progressive multifocal leukoencephalopathy Answer: d. The symptoms are most representative of MAI so a workup with liver biopsy or bone marrow biopsy is indicated.

19. For which patient do you not need to give antibiotic prophylaxis for infective endocarditis? a. Prosthetic valve b. Previous endocarditis c. Major dental extractions d. Infected skin surgery e. Flexible colonoscopy Answer: e. For all flexible endoscopies, there is no need to give antibiotic prophylaxis for infective endocarditis.

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20. You need to provide antibiotic prophylaxis for a patient with a prosthetic heart valve in order to prevent infective endocarditis. Which antibiotic would least be chosen? a. Amoxicillin b. Ciprofloxacin c. Clindamycin d. Azithromycin e. Cephalexin Answer: b. Each of these is effective as prophylaxis against infective endocarditis except for ciprofloxacin, which does not have good coverage for things like staphylococcus.

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