Antibiotics: Friends And Foes

As Dental practitioners we sometimes get very complacent with the use of antibiotics. When patients come in with pain, swelling, erythema, and other signs of infection, it’s almost a knee-jerk reaction to place this patient on an antibiotic. It is sometimes helpful to review basic indications for antibiotics as well as guidelines for appropriate therapy. We have very limited space for this review and therefore it is not comprehensive, and we should refer back to our current therapeutic guidelines as well as training on appropriate antibiotic use.

The first principle of antibiotic use is to determine if there is in fact an infection. I have treated several patients who had classic signs and symptoms of acute temporomandibular joint disorders when in fact they had a mild odontogenic infection associated with an irreversible pulpitis on a mandibular molar and all they really required was extraction or endodontic therapy. It’s important that we are confident that there is in fact an infection to be treated before routinely prescribing antibiotics.

The second principle of antibiotic use is to determine the current state of the hosts’ defenses. Many times an odontogenic infection can be treated surgically by removing the source of the infection if the patient is not immunocompromised. There are however, an increasing number of patients who are immunocompromised because of the immunosuppressive drugs associated with cancer treatment, suppression of autoimmune disorders such as rheumatoid arthritis, ulcerative colitis, diabetes, and immunosuppression due to alcoholism or drug addiction.

The third principle of antibiotic use is to always remember that surgical intervention is many times necessary in addition to, or in place of, antibiotic therapy. Endodontic therapy, extraction, or debridement of necrotic bone is the primary form of treatment in addition to antibiotic coverage as indicated.

The fourth principle of antibiotic therapy is to identify the causative organism if it is at all possible. This means that incision, drainage, with appropriate cultures that many include hard and soft tissue samples as well is very important particularly in cases where the patient is failing to improve with appropriate antibiotics. Culture tubes along with appropriate sample bottles can be obtained from your local hospital microbiology lab or you may choose to refer the patient to an Oral & Maxillofacial surgeon for appropriate identification of causative organisms. Included in the identification of the organism is typically a sensitivity screening to common antibiotics and this can prove very helpful in providing the appropriate choice of antibiotics.

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The fifth principle of antibiotic use is to choose a specific, narrow-spectrum antibiotic with the least toxic side effects that is appropriate for the suspected causative agents. This obviously includes choosing an antibiotic for which the patient has no history of allergy. This minimizes the risk of super infections and the risk of developing other resistant bacteria. We are all familiar with the propensity of clindamycin for the development of pseudomembranous colitis, however, it is just as common with the use of broad-spectrum penicillin’s and cephalosporins simply because these antibiotics are used more frequently.

The sixth principle of antibiotic use is to use a bactericidal antibiotic rather than a bacteriostatic antibiotic whenever possible. Commonly used bactericidal antibiotics in the dental profession are penicillin’s, cephalosporins, metronidazole, and ciprofloxacin. Bacteriostatic antibiotics are the tetracyclines, the macrolides such as erythromycin and azithromycin, clindamycin and sulfa antibiotics.

The seventh principle of antibiotic use is to give the proper dose of the antibiotic to achieve three to four times the minimum inhibitory concentration in the patient’s plasma and this is usually determined by the standard prescription protocol for the particular drug. Unfortunately, this is also dependent on patient cooperation and taking the antibiotic as prescribed. It is also important to remember that most antibiotics are cleared through the kidneys and patients with pre-existing renal disease and subsequent decreased renal clearance may require longer intervals between doses if overdosing is to be avoided.

The eight principle of antibiotic use is to monitor the patient. For example, it has been suggested that if a patient fails to improve significantly with a mild or moderate infection after 48 hours of use of a single therapeutic that consideration should