Lien Cattoir

Therapeutic drug monitoring of voriconazole: validation of a novel ARK™ immunoassay and comparison with ultra-high performance liquid chromatography.

Voriconazole (VRC) is a second-generation triazole licensed to treat patients with invasive aspergillosis, invasive candiadiasis caused by Candida species with reduced susceptibility to fluconazole, and serious infections caused by Scedosporium and Fusarium species [1, 2]. Recently, prophylaxis of invasive fungal infections (IFIs) in high risk allogeneic hematopoietic stem cell transplant recipients was added as a new indication for VRC [3]. According to the British Society for Medical Microbiology (BSMM), trough concentrations > 1 mg/L and < 4–6 mg/L are required to maximize efficacy and to minimize drugrelated toxicity [4]. In patients treated for IFIs with the recommended oral/intravenous VRC dosage regimen, large interand intra-individual variability has been found in VRC trough plasma concentrations, ranging from undetectable concentrations to 11 mg/L [5]. Oral bioavailability is a major determinant of variability of VRC plasma concentrations [6]. In healthy individuals, oral bioavailability is reported to be high, approximately 96%, when administered in a fasting state (1 h before/after meal) [2]. However, in patients, oral bioavailability might be much lower, as these patients are frequently suffering from gastro-intestinal complications [6, 7]. Other factors that contribute to the variability in VRC plasma concentrations are the Michaelis-Menten (non-linear) pharmacokinetics of VRC, polymorphisms of the gene encoding the CYP2C19 enzyme, drug-drug interactions, liver disease and age [4]. The large variability in VRC plasma concentrations together with the narrow therapeutic window for treating patients with IFIs, makes individualized dosing adjustments based on therapeutic drug monitoring (TDM) of VRC necessary to optimize therapeutic response and to minimize the probability of neurotoxicity [6]. According to the BSMM, VRC plasma concentrations should be measured in the first 5 days of therapy and regularly thereafter [4]. In Table 1, an overview is given of the analytical methods that are suitable for measuring VRC in plasma, including bioassays [8–11], HPLC [12–19] and LC-MSMS [20– 29] methods. Currently, chromatographic methods are predominantly used, as can also be derived from proficiency testing results [30]. These techniques are accurate, precise and allow the simultaneous analysis of multiple antifungal drugs. However, these methods also include some disadvantages, such as the limited availability of chromatographic instruments in the core clinical laboratory, the need for skilled laboratory technicians, the use of (sometimes) time consuming sample preparation steps and the need aCurrent address: Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, Ghent, Belgium *Corresponding author: Veronique Stove, Department of Laboratory Medicine, Ghent University Hospital, De Pintelaan 185 (2P8), 9000 Ghent, Belgium, Phone: +32 9 3325871, Fax: +32 3324985, E-mail: Veronique.Stove@UGent.be Lien Cattoir and Alain G. Verstraete: Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium; and Department of Clinical Chemistry, Microbiology and Immunology, Ghent University, Ghent, Belgium Gregoire Fauvarque: Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium Simon Degandt and Timothy Ghys: Clinical Laboratory, General Hospital Sint-Lucas Ghent, Ghent, Belgium

Surveillance of Endoscopes: Comparison of Different Sampling Techniques

OBJECTIVE To compare different techniques of endoscope sampling to assess residual bacterial contamination. DESIGN Diagnostic study. SETTING The endoscopy unit of an 1,100-bed university hospital performing ~13,000 endoscopic procedures annually. METHODS In total, 4 sampling techniques, combining flushing fluid with or without a commercial endoscope brush, were compared in an endoscope model. Based on these results, sterile physiological saline flushing with or without PULL THRU brush was selected for evaluation on 40 flexible endoscopes by adenosine triphosphate (ATP) measurement and bacterial culture. Acceptance criteria from the French National guideline (<25 colony-forming units [CFU] per endoscope and absence of indicator microorganisms) were used as part of the evaluation. RESULTS On biofilm-coated PTFE tubes, physiological saline in combination with a PULL THRU brush generated higher mean ATP values (2,579 relative light units [RLU]) compared with saline alone (1,436 RLU; P=.047). In the endoscope samples, culture yield using saline plus the PULL THRU (mean, 43 CFU; range, 1–400 CFU) was significantly higher than that of saline alone (mean, 17 CFU; range, 0–500 CFU; P<.001). In samples obtained using the saline+PULL THRU brush method, ATP values of samples classified as unacceptable were significantly higher than those of samples classified as acceptable (P=.001). CONCLUSION Physiological saline flushing combined with PULL THRU brush to sample endoscopes generated higher ATP values and increased the yield of microbial surveillance culture. Consequently, the acceptance rate of endoscopes based on a defined CFU limit was significantly lower when the saline+PULL THRU method was used instead of saline alone. Infect Control Hosp Epidemiol 2017;38:1062–1069

Hepatitis E virus serology and PCR: does the methodology matter?

Hepatitis E virus (HEV) genotype 3 is an emerging pathogen in the developed world. As the clinical manifestations and routine laboratory parameters are often nonspecific, accurate diagnostic tests are crucial. In the current study, the performance of six serological assays and three PCR assays for the detection of HEV was evaluated. In the setting of the Ghent University Hospital, patients with clinically suspected HEV infection were tested for the presence of HEV IgM and IgG as well as HEV RNA. Serology was performed using six commercial HEV ELISA assays: Biorex, Wantai and Mikrogen IgM and IgG. HEV RNA was detected using one commercial assay (Altona RealStar®), and two optimized in-house real-time RT-PCR assays (according to Jothikumar et al., 2006 and Gyarmati et al., 2007). In addition, all three PCR assays were performed on 16 external quality control (EQC) samples. In a period of 39 months (January 2011-April 2014), 70 patients were enrolled. Using different ELISA assays, the prevalence of antibodies varied from 5.7% to 14.3% for HEV IgM and from 15.7% to 20.0% for IgG. All but two of the results of the PCR assays performed on clinical samples agreed. However, 10 out of 16 EQC samples results showed major discrepancies. We observed important differences in the performance of various serological and PCR assays. For this reason, results of both serological and molecular tests for HEV should be interpreted with caution.

Influence of physical properties of cuvette surface on measurement of serum lipase

Abstract Background: Despite striking similarities among colorimetric lipase assay recipes, marked intervendor differences are noted in the reported lipase values. In the present study, the effect of physical properties of the cuvette surface on measurement of serum lipase was investigated. Methods: Lipase activity was measured concomitantly in cuvettes from three different analyzers: Vista (Siemens), Modular (Roche), and Synchron (Beckman Coulter). The surface/volume ratio of the cuvettes and the contact angle of the cuvette polymers were determined. The effects of various characteristics of serum (biochemical parameters, surface tension) were also examined. Results: Serum lipase activities based on the colorimetric methylresorufin assay differed markedly according to the cuvettes used. More specifically, in the lower activity rate, marked differences were reported. The physical properties of the various cuvettes showed remarkable differences, especially in the contact angles. Other biochemical parameters (bilirubin, alkaline phosphatase, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides) and serum surface tension did not affect the results. Conclusions: Serum lipase activity is affected by the physical properties of the cuvette surface.

Clinical burden of hepatitis E virus infection in a tertiary care center in Flanders, Belgium

BACKGROUND Hepatitis E virus (HEV) infection is increasingly recognized as a cause of hepatitis in developed countries. A high HEV IgG seroprevalence in humans and pigs is reported as well as sporadic clinical cases of autochtonous HEV but there are currently no data available on the clinical burden of HEV in Belgium. OBJECTIVES The objective of the current study was to evaluate the actual clinical burden of HEV infections in our tertiary care center in Flanders, Belgium. STUDY DESIGN In the setting of Ghent University Hospital, patients were assessed for the presence of HEV IgG and IgM as well as HEV RNA if no other cause was found for one of the following clinical presentations: a) elevation of liver enzymes in post-liver transplant; b) suspicion of acute or toxic hepatitis; c) unexplainable elevation of liver enzymes; d) cirrhosis with acute-on-chronic exacerbation. RESULTS In a period of 39 months (January 2011-April 2014) 71 patients were enrolled. HEV IgG was found positive in 13 (18,3%) patients; HEV IgM in 6 patients (8,5%) and HEV RNA in 4 (5,6%) patients. All HEV IgM/RNA positive patients were male, aged 41-63, and classified in the clinical groups a), b) or d). HEV IgG seroprevalence was slightly higher but not significantly different from the seroprevalence in the general population in this region in Belgium previously reported to be 14% (p-value 0.41) by our group. CONCLUSIONS HEV should be considered as a cause of liver pathology especially in middle-aged men with elevation of liver enzymes.

Improving timelines in reporting results from positive blood cultures: simulation of impact of rapid identification on therapy on a real-life cohort

For patients with bloodstream infections, rapid initiation of the appropriate antimicrobial therapy is essential in reducing mortality and morbidity. New developments and automation in clinical microbiology labs speed up the identification and susceptibility results but are expensive. To gain insight in the added value of the new workflows, we simulated the possible impact of rapid identification and susceptibility tests on a real-life cohort of 158 positive blood culture episodes. Our routine workflow was theoretically challenged against two new workflows, one based on rapid identification with MALDI-TOF MS and one based on molecular testing. First, we observed an important role of the rapid communication of the gram stain results, as about one third of patients needed an adaptation of the antimicrobial therapy based on these results. Antibiotic adaptation based on the microorganism identification was necessary in 10% and in another 25% of cases after the availability of the susceptibility results. The added value of the newer workflow methods lies mainly in the field of the rapid identification and was rather limited in our cohort. In conclusion, for optimizing the blood culture workflow, each microbiology lab should critically scan its own workflow and know its own blood culture epidemiology, before investing in expensive or time-consuming processes.

Epidemiology of RSV and hMPV in Belgium: a 10-year follow-up

ABSTRACT Objectives: Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are important respiratory pathogens. Both viral pathogens have similar clinical manifestations. The epidemiology of RSV is well known, that of hMPV is less clear. We reviewed the results of 10 consecutive years of molecular testing for RSV and hMPV in respiratory samples of Flemish patients. Methods: In the laboratory of the OLV hospital Aalst, Belgium, multiplex RT-PCR assays are used for the detection of RSV and hMPV. The lab receives invasive and noninvasive respiratory samples of patients from all over Flanders. Results: Between September 2006 and August 2016, 16,826 respiratory samples were analyzed for RSV and hMPV. Of these samples, 18% tested positive for RSV and 7.3% for hMPV. RSV consistently peaked in November/December each year within a very narrow time frame. The occurrence of hMPV was less predictable and spreaded more widely throughout the winter and spring. Both viruses were mainly found in samples from young children. RSV was most frequently detected in samples from infants <3 months, while hMPV peaked between 6 and 9 months. After the age of 1 year, RSV rapidly dropped. hMPV dropped a little later and slower. Both viruses slightly increased again at older age (>50 years). Conclusions: Despite their similarities, some of the epidemiologic characteristics of hMPV and RSV differ. The most striking difference is the annual distribution of RSV and hMPV infections.

Anti-K-antistoffen bij de zwangere: belang van strikte follow-up van de foetus en de neonaat

Anti-K-antistoffen kunnen leiden tot ernstige hemolytische ziekte bij de foetus en de neonaat (HZF/N). Het feit dat naast immuunafbraak van rode bloedcellen (RBC) ook onderdrukking van de foetale erytropoese een rol speelt in de pathogenese, maakt de diagnose, de aanpak en de opvolging bij anti-K-alloantistoffen enigszins afwijkend in vergelijking met andere onregelmatige antistoffen. Een 36-jarige zwangere vrouw werd verwezen naar een tertiair ziekenhuis wegens foetale cardiomegalie en ascites. Een analyse van het maternale bloed toonde de aanwezigheid van anti-K-antistoffen. Een uitgebreid echografisch onderzoek, waaronder een dopplermeting van de pieksystolische snelheid ter hoogte van de arteria cerebri media (MCA-PSV), wees op hydrops foetalis als gevolg van ernstige foetale anemie. De foetus kreeg vier intra-uteriene transfusies (IUT’s). Bij de geboorte was er geen anemie. Het postnatale verloop leek onverwikkeld. Een laboratoriumanalyse toonde aanvankelijk enkel uitgesproken reticulocytopenie. Na enige tijd ontwikkelde er zich toch neonatale anemie, waarvoor er twee RBC-transfusies nodig waren. Deze casus illustreert het belang van een vroegtijdige doorverwijzing en een strikte opvolging van zwangere vrouwen met gekende of nieuw gediagnosticeerde anti-K-antistoffen. Daarenboven wordt aangetoond dat alle aangetaste pasgeborenen, ongeacht het klinische verloop, na de geboorte zorgvuldig opgevolgd moeten worden. Deze aanpak heeft een belangrijke impact op de foetale en de neonatale prognose.

Epstein-Barr virus serology and PCR: conflicting results in an immunocompetent host. A case report and review of literature.

Abstract We present the case of a 27-year-old immunocompetent man who progressively developed a generalized lymphadenopathy and B symptoms. Results of Epstein–Barr virus (EBV) serology were suggestive for a past infection, but the EBV viral load in whole blood was high. Also, core needle biopsy of the largest lymph node showed an image which could fit an EBV-driven reactive lymphoproliferation. Despite the absence of an immune disorder, all medical evidence points to an EBV-driven lymphoproliferative proces. In immunocompetent patients, it seems extremely uncommon to detect a high EBV viral load in the absence of serological evidence of an acute EBV infection or reactivation. We reviewed literature on this topic and on the selection of the appropriate sample type for EBV PCR, as this is known to be a critical point. Serological testing for the diagnosis of EBV infection is the gold standard in immunocompetent patients. Measuring EBV viral load is only recommended when dealing with immunocompromised patients. Although extremely rare, this case report shows that there is a place for EBV PCR in certain situations in immunocompetent patients. Besides, there is still no consensus regarding the specimen of choice for the determination of the EBV viral load. The preferred specimen type seems to depend on the patient’s underlying condition.