KLINISCH LABORATORIUM

CENTRUM KLINISCH LABORATORIUM

ARTIKELS

ABSTRACT 1

Interference of anti-streptavidin antibodies in immunoassays: a very rare phenomenon or a more common finding?

Verougstraete N, Berth M, Delanghe J, Callewaert N, et al. Clinical Chemistry and Laboratory Medicine, 2020, 58(10), 1673-1680

INTRODUCTION Anti-streptavidin antibodies (ASA) may cause analytical interference on certain immunoassay platforms. Streptavidin is purified from the non-pathogenic Streptomyces avidinii soil bacterium. In contrast to interference with biotin, ASA interference is supposed to be much rarer. In-depth studies on this topic are lacking. Therefore, we carried out an analysis toward the prevalence and the possible underlying cause of this interference.

MATERIALS/METHODS Anti-streptavidin (AS)-immunoglobulin G (IgG) and AS-IgM concentrations were determined on multiple samples from two patients with ASA interference and on 500 random samples. On a subset of 100 samples, thyroid-stimulating hormone (TSH) was measured on a Cobas analyzer before and after performing a neutralization protocol which removes ASA. The relationship between the ratio of TSH after neutralization/TSH before neutralization and the ASA concentration was evaluated. Subsequently, an extract of S. avidinii colonies was analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting.

RESULTS A positive correlation between AS-IgM concentrations and TSH ratio was obtained. Eight samples out of 500 exceeded the calculated AS-IgM cut-off value. In comparison to the AS-IgM concentrations in the population, titers from the two described cases clearly stood out. The isolated cases represent the end of a broader spectrum as there is a continuum of AS-IgM reactivity in the general population. We could not observe any differences in the immunoblot patterns between the cases and controls, which may indicate the general presence of ASA in the population.

CONCLUSION Interference due to ASA is more prevalent than initially thought and is caused by IgM antibodies. ABSTRACT 2

Quality of blood samples collected at home does not affect clinical decision making for the administration of systemic cancer treatment.

Cool L, Callewaert N, Pottel H, Van Eygen K, et al. Scandinavian Journal of Clinical and Laboratory Investigation, 2020, 80(3), 215-221

OBJECTIVE The aim of this exploratory clinical study was to evaluate whether the preanalytical quality of blood samples subjected to delayed centrifugation and transport – as a result of home-sampling – is affected in a way it alters the clinical decision-making for oncological home-hospitalization.

MATERIALS/METHODS Forty-nine patients with cancer donated two additional blood samples during their ambulatory hospital visit. Fifteen blood analytes were compared between routine blood samples and samples that were subjected to transport and delayed centrifugation in order to mimic a locally implemented model for oncological home-hospitalisation. Deviations were analysed by means of Deming regression. For those analytes showing statistically significant intercepts and/or slopes, the mean deviations were compared to the desirable analytical bias; and the intra-individual differences were compared with the limits for clinical decision-making.

RESULTS Statistically significant intercepts and/or slopes were observed for haematocrit (HCT), mean cellular volume (MCV), platelets count (PLT) and C-reactive protein (CRP). Differences exceeding the allowable margins of desirable analytical bias were observed for HCT and MCV. Risk of different clinical decision-making couldn’t be observed for any of the analytes showing statistically significant differences.

CONCLUSION These results demonstrate that home-collection of blood samples, transported at room temperature and centrifuged within a mean time of five hours after sampling, has no effect on clinical decision-making with regards to systemic cancer therapy. However, attention should be paid to the potential occurrence of haemolysis during the preanalytical phase, which can negatively influence haemolysis-dependent variables.

ABSTRACT 3

An unconscious man with profound drug-induced hypoglycaemia.

Schiemsky T, Vundelinckx G, Croes K, et al. Biochemia Medica, 2020, 30(1), DOI: 10.11613/ BM.2020.010802

INTRODUCTION Hypoglycaemia has been reported as an unusual complication of tramadol use and in a few cases of tramadol poisoning, but the exact mechanism is not known. An ambulance crew was dispatched to an unconscious 46-year old man. A glucometer point-of-care measurement revealed a profound hypoglycaemia (1.9 mmol/L). Treatment with intravenous glucose was started and the patient was transported to the hospital. The patient had several episodes of pulseless electrical activity requiring cardiopulmonary resuscitation in the ambulance and upon arrival in the hospital. Despite continuous glucose infusion the hypoglycaemia was difficult to correct during the next few hours and the patient developed hypokalaemia. Further investigation to identify the cause of hypoglycaemia revealed that insulin and C-peptide were inappropriately raised. A toxicological investigation revealed the presence of tramadol and its metabolites in lethal concentrations. Also acetaminophen, ibuprofen and lormetazepam were present. Ethanol screening was negative (< 0.1 g/L) and no sulfonylurea were detected. The patient developed multiple organ failure, but eventually recovered.

MATERIALS/METHODS The hypoglycaemia was caused by inappropriate stimulation of insulin secretion in a patient intoxicated with tramadol. The sudden hypokalaemia was caused by a massive intracellular shift of potassium in response to the hyperinsulinemia, triggered by the intravenous administration of glucose.

CONCLUSION To our knowledge, we are the first to document a significant rise in endogenous insulin production in a hypoglycaemic patient presenting with tramadol intoxication. Our observation suggests that hyperinsulinemia could be the cause of the hypoglycaemia associated with tramadol use. ABSTRACT 4

Interpretation of EBV serology for human body material donors: is there a need for early antigen IgG and heterophile antibodies testing?

Verougstraete N, Padalko E, Coorevits L Cell and tissue banking, 2020, 21(1), 167-169

ABSTRACT In this report we evaluated a diagnostic algorithm, proposed by the Belgian Superior Health Council, to detect acute and past Epstein-Barr virus (EBV) infections by means of serology in donors of human body material for transplantation. The available EBV serology parameters were tested on eighty serum samples on three random access analysers: Architect i2000 SR, Liasion XL and BioPlex 2200. The EBV sero-status was determined according to the proposed algorithm and results were compared between the different analysers. Seventy one % of the samples gave concordant interpretations on the three analysers. Most of the discordant results were attributable to early antigen (EA) IgG. The knowledge of the EA IgG and heterophile antibodies (HA) IgM status provided only limited added value and was only useful to distinguish between a very early acute infection and false positivity of viral capsid antigen IgM. The diagnostic algorithm proposed by the Belgian Superior Health Council is merely directive and each individual lab remains responsible for the interpretation and implementation of test combinations for the detection of EBV infections. Our study shows the limited added value of testing for EA IgG and HA IgM, based both on clinical and technical performance.

ABSTRACT 5

To pool or not to pool? Screening of Chlamydia trachomatis and Neisseria gonorrhoeae in female sex workers: pooled versus single-site testing.

Verougstraete N, Verbeke V, De Cannière A-S, Coorevits L, et al. Sexually transmitted infections, 2020, 96(6), 417-421

INTRODUCTION As Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the most commonly reported STIs in Belgium and the majority of women infected are asymptomatic, targeted screening of patients in specified risk groups is indicated. To prevent long-term complications and interrupt transmission, extragenital samples should be included. As this comes with a substantial extra cost, analysis of a pooled

sample from vaginal and extragenital sites could be a solution. In this study, we evaluated the feasibility of molecular testing for CT and NG in pooled versus single-site samples in a large cohort of female sex workers.

MATERIALS/METHODS Women were sampled from three anatomical sites: a pharyngeal, a vaginal and a rectal swab. Each sample was vortexed, and 400 µL of transport medium from each sample site was pooled into an empty tube. NAAT was performed using the Abbott RealTime CT/NG assay on the m2000sp/rt system.

RESULTS We included 489 patients: 5.1% were positive for CT; 2.0% were positive for NG and 1.4% were coinfected, resulting in an overall prevalence of 6.5% (95% CI 4.5% to 9.1%) for CT and 3.5% (95% CI 2.0% to 5.5%) for NG. From the 42 patients positive on at least one non-pooled sample, only 5 gave a negative result on the pooled sample, resulting in a sensitivity of 94% (95% CI 79% to 99%) for CT and 82% (95% CI 57% to 96%) for NG. The missed pooled samples were all derived from single-site infections with low bacterial loads. The possibility of inadequate self-sampling as a cause of false negativity was excluded, as 4/5 were collected by the physician. Testing only vaginal samples would have led to missing 40% of CT infections and 60% of NG infections.

CONCLUSION Pooling of samples is a cost-saving strategy for the detection of CT and NG in women, with minimal decrease in sensitivity. By reducing costs, more patients and more extragenital samples can be tested, resulting in higher detection rates.

ABSTRACT 6

Tintelnotia destructans as an emerging opportunistic pathogen: first case of T. destructans superinfection in herpetic keratitis.

Roels D, Coorevits L, Lagrou K, et al. American Journal of Ophthalmology Case Reports, 2020, DOI: 10.1016/j.ajoc.2020.100791

INTRODUCTION Only recently Tintelnotia was described as a new genus in the Phaeosphaeriaceae family of fungi containing two species, T. opuntiae and T. destructans. Until now, T. destructans keratitis was associated with contact lens wear and ocular trauma. We present the first case of T. destructans keratomycosis presenting as a superinfection in herpetic keratitis.

RESULTS We present a case of a 53-year-old woman who presented with a unilateral keratitis since 3 weeks without history of trauma or contact lens wear, not responding to topical ofloxacin. Polymerase Chain Reaction (PCR) of the corneal ulcer was positive for Herpes Simplex Virus type 1 (HSV-1). Signs and symptoms progressively improved after starting topical and systemic antiviral therapy. Six weeks later however, our patient presented with a new white infiltrate in the previous herpetic epithelial defect. In vivo confocal microscopy showed fungal hyphae and culture from corneal scrapings identified a hyphomycete. Intensive antimycotic therapy could not prevent a corneal perforation 1 week later. Penetrating keratoplasty was performed with intracameral injection of amphotericin B. Culture of the corneal button and PCR and sequence analysis on the fungal isolate confirmed the diagnosis of T. destructans keratomycosis. Six months after penetrating keratoplasty, biomicroscopy showed a clear graft without recurrence of fungal activity.

CONCLUSION T. destructans is an emerging opportunistic pathogen causing severe keratomycosis. Despite intensive antimycotic therapy, rapid progression to corneal perforation can be seen. Early diagnosis using confocal microscopy, fungal culture and PCR can allow prompt initiation of treatment, which should be guided by in vitro susceptibility testing.

ABSTRACT 7

Sensitivity and specificity of 14 SARS-CoV-2 serological assays and their diagnostic potential in RT-PCR negative COVID-19 infections.

Van Honacker E, Coorevits L, Boelens J, et al. Acta Clinica Belgica, 2020, Dec 22, DOI: 10.1080/17843286.2020.1861885

INTRODUCTION Molecular detection of SARS-CoV-2 in respiratory samples is the gold standard for COVID-19 diagnosis but it has a long turnaround time and struggles to detect low viral loads. Serology could help to diagnose suspected cases which lack molecular confirmation. Two case reports are presented as illustration.

OBJECTIVE The aim of this study was to evaluate the performance of several commercial assays for COVID-19 serology. We illustrated the added value of COVID-19 serology testing in suspect COVID-19 cases with negative molecular test.

MATERIALS/METHODS Twenty-three sera from 7 patients with a confirmed molecular diagnosis of SARS-CoV-2 were tested using 14 commercial assays. Additionally, 10 pre-pandemic sera and 9 potentially cross-reactive sera were selected. We calculated sensitivity and specificity. Furthermore, we discuss the diagnostic relevance of COVID-19 serology in a retrospective cohort of 145 COVID-19 cases in which repetitive molecular and serological SARS-CoV-2 tests were applied.

RESULTS The interpretation of the pooled sensitivity of IgM/A and IgG resulted in the highest values (range 14-71% on day 2-7; 88-94% on day 8-18). Overall, the specificity of the assays was high (range 79-100%). Among 145 retrospective cases, 3 cases (2%) remained negative after sequential molecular testing but positive on final SARS-CoV-2 serology.

CONCLUSION Sensitivity of COVID-19 serological diagnosis was variable but consistently increased at >7 days after symptom onset. Specificity was high. Our data suggest that serology can complement molecular testing for diagnosis of COVID19, especially for patients presenting the 2nd week after symptom onset or later.

ABSTRACT 8

Toilet drain water as a potential source of hospital roomto-room transmission of carbapenemase-producing Klebsiella pneumoniae.

Heireman L, Hamerlinck H, Coorevits L, et al. The Journal of Hospital Infection, 2020, 106(2), 232-239

INTRODUCTION Carbapenemase-producing Enterobacterales (CPE) have rapidly emerged in Europe, being responsible for nosocomial outbreaks.

OBJECTIVE Following an outbreak in the burn unit of Ghent University Hospital, we investigated whether CPE can spread between toilets through drain water and therefrom be transmitted to patients.

MATERIALS/METHODS In 2017, the burn centre of our hospital experienced an outbreak of OXA-48-producing Klebsiella pneumoniae that affected five patients staying in three different rooms. Environmental samples were collected from the sink, shower, shower stretcher, hand rail of the bed, nursing carts, toilets, and drain water to explore a common source. Whole-genome sequencing and phylogenetic analysis was performed on K. pneumoniae outbreak isolates and two random K. pneumoniae isolates.

RESULTS OXA-48-producing K. pneumoniae was detected in toilet water in four out of six rooms and drain water between two rooms. The strain persisted in two out of six rooms after two months of daily disinfection with bleach. All outbreak isolates belonged to sequence type (ST) 15 and showed isogenicity (<15 allele differences). This suggests that the strain may have spread between rooms by drain water. Unexpectedly, one random isolate obtained from a patient who became colonized while residing at the geriatric ward clustered with the outbreak isolates, suggesting the outbreak to be larger than expected. Daily application of bleach tended to be superior to acetic acid to disinfect toilet water; however, disinfection did not completely prevent the presence of carbapenemase-producing K. pneumoniae in toilet water.

CONCLUSION Toilet drain water may be a potential source of hospital room-to-room transmission of carbapenemase-produ- cing K. pneumoniae.

ABSTRACT 9

Evaluation of QuantiFERON-TB Gold Plus on Liaison XL in a low-tuberculosis-incidence setting.

De Maertelaere E, Vandendriessche S, Verhasselt B, Coorevits L, et al. Journal of Clinical Microbiology, 2020, 58(4), 1-2

INTRODUCTION The QuantiFERON-TB Gold Plus assay (QFT; Qiagen, Hilden, Germany) is a frequently used interferon gamma releasing assay (IGRA) for the diagnosis of latent tuberculosis infections (LTBI) (1, 2). Recently, it became available on Liaison XL (DiaSorin S.p.A., Saluggia, Italy), a fully automated analyzer

using chemiluminescense detection within a chemiluminescent immunoassay (CLIA).

OBJECTIVE In this study, we compared this novel method to the commonly used enzyme-linked immunosorbent assay (ELISA) in a low-incidence LTBI setting.

MATERIALS/METHODS Heparin blood samples (n 92) taken for routine QFT assays were analyzed with both assays on two different sites as follows: after incubation and centrifugation as instructed by the manufacturer, QFT CLIA was performed on-site (Ghent University Hospital, Belgium) on one aliquot of the processed plasma sample, while another aliquot was transported at room temperature to site two (University Hospital of Leuven, Belgium) for QFT ELISA on the BEP III platform (Siemens Healthcare Diagnostics, Eschborn, Germany). Results were interpreted according to the manufacturer’s criteria (positivity threshold 0.35).

RESULTS Of the 92 samples, 46 were from males and 42 from females, median age of 45 years (range 1 to 91 years). Four samples were from encoded health care workers sent by the occupational medicine department. Eighty-seven samples (95%) returned concordant results: 12 positive, 71 negative, and 4 indeterminate results. Five samples (5%) were discordant (Table 1), of which four samples resulted in a major discrepancy, i.e., positive versus negative. Clinical information on these samples did not bring clarity and follow-up samples were not included within the scope of this comparison. However, the discordant samples were all lowpositive results which, when applying a suitable additional range, could be classified as borderline.

CONCLUSION In conclusion, the QFT CLIA on Liaison XL showed comparable performance to detection with QFT ELISA in a low LTBI incidence setting. There is need to define a borderline range, which possibly needs to be adjusted according to the incidence setting and the detection method, and should be based on clinical diagnostics criteria.

PRESENTATIES

ABSTRACT 10

Evaluation of the Xpert HBV VL test for cartridge-based quantitative HBV DNA analysis on plasma.

Wallaert A, De Bel A, Boudewijns M October 2020, European Meeting on Molecular Diagnostics, Noordwijk - Nederland

ABSTRACT 11

Whole transcriptome profiling of liquid biopsies from tumor xenografted mouse models enables specific monitoring of tumor-derived RNA.

Deleu J, Vermeirssen V, Van Maerken T, et al. October 2020, SIOP 2020: 52th annual meeting of the International Society of Paediatric Oncology, Online

ABSTRACT 12

Burkholderia cepacia outbreak due to contaminated wash gloves.

Echahidi F, Peeters C, De Bel A, Boudewijns M, et al. December 2020, Réunion Interdisciplinaire de Chimiothérapie Anti-Infectieuse 2020, Parijs - Frankrijk

INTRODUCTION Burkholderia cepacia complex (BCC) bacteria cause infections in cystic fibrosis patients as well as in hospitalised immunocompromised patients. BCC can spread among hospitalised patients through contaminated liquids, surfaces and person-to-person transmission. We describe 2 episodes of B. cepacia outbreak at a Belgian intensive care unit due to contaminated wash gloves.

OBJECTIVE We describe 2 episodes of B. cepacia outbreak at a Belgian intensive care unit due to contaminated wash gloves.

MATERIALS/METHODS Samples from 9 patients hospitalised during April-Mai 2019 and during January 2020 as well as suspected lots of wash gloves and other hygienic products were tested for bacterial contamination. BCC isolates were tested by MALDI-TOF MS (Bruker) for identification and genotyped by Random Amplification of Polymorphic DNA.

The identification and genotyping were confirmed by recA gene sequence analysis and multi-locus sequence typing, respectively.

RESULTS At the first outbreak episode, B. contaminans was found in 2 patients and B. cepacia in 5 patients. One out of 2 tested packagings of wash gloves was culture positive and the isolate was identified as B. cepacia. RAPD results showed an identical pattern in 4 patients isolates as well as in the wash glove isolate tested. In 1 patient isolate a different RAPD pattern was obtained. MLST confirmed the RAPD results; the 4 B. cepacia patients isolates and the wash glove isolate belonged to ST-1649 and 1 patient isolate, with a different RAPD pattern, belonged to ST-767. The wash gloves company confirmed the contamination of one lot by Burkholderia. Subsequently, the company promised to take measures to avoid future contamination. At the second outbreak episode B. cepacia ST-767 was isolated from 2 patients and 1 out of 4 tested lots of wash gloves yielded both B. cepacia ST-767 and ST-1649.

CONCLUSION Contaminated wash gloves were the most likely source of the 2 B. cepacia outbreak episodes and contamination seems to occur at the manufacturing process. A similar outbreak linked to contaminated wash gloves has been recently described (1). Possible link between the current and the previously described outbreak should be investigated. The wash gloves company denied BCC contamination at the second outbreak episode. Subsequently, we stopped using these wash gloves and we advise other hospitals to check same products for BCC contamination.