J. Frans

Comparison of six different calprotectin assays for the assessment of inflammatory bowel disease

Background and objectives Faecal calprotectin is a valuable noninvasive marker for inflammatory bowel disease (IBD). The aim of our study was to determine the correlation between six different calprotectin assays and compare their performance for diagnosis and follow up of IBD. Methods Thirty-one patients with suspected IBD and 31 patients in follow up were included. We determined calprotectin by means of three rapid immmunochromatographic tests, two enzyme-linked immunosorbent assays, and one automated fluoroimmunoassay. Results were correlated with endoscopic and histological findings. Results Although all methods correlated significantly, slopes and intercepts differed extensively, with up to 5-fold quantitative differences between assays. Sensitivity and specificity for diagnosis of IBD were 82–83 and 84–89%, respectively. For follow up, sensitivity in detecting mild ulcerative colitis was 71–100%. In moderate-to-severe ulcerative colitis, sensitivity was 100% for all assays. Specificity was 67–86% in both subgroups. In Crohn’s disease, only moderate-to-severe disease could be differentiated from remission, with sensitivity 83–86% and specificity 75% for all tests. Conclusions All calprotectin assays showed comparable clinical performance for diagnosis of IBD. For follow up, performance was acceptable, except for mild Crohn’s disease. Because of the large quantitative differences, further efforts are needed to standardize calprotectin assays.

The preanalytical optimization of blood cultures: a review and the clinical importance of benchmarking in 5 Belgian hospitals

Bloodstream infections remain a major challenge in medicine. Optimal detection of pathogens is only possible if the quality of preanalytical factors is thoroughly controlled. Since the laboratory is responsible for this preanalytical phase, the quality control of critical factors should be integrated in its quality control program. The numerous recommendations regarding blood culture collection contain controversies. Only an unambiguous guideline permits standardization and interlaboratory quality control. We present an evidence-based concise guideline of critical preanalytical determinants for blood culture collection and summarize key performance indicators with their concomitant target values. In an attempt to benchmark, we compared the true-positive rate, contamination rate, and collected blood volume of blood culture bottles in 5 Belgian hospital laboratories. The true-positive blood culture rate fell within previously defined acceptation criteria by Baron et al. (2005) in all 5 hospitals, whereas the contamination rate exceeded the target value in 4 locations. Most unexpected, in each of the 5 laboratories, more than one third of the blood culture bottles were incorrectly filled, irrespective of the manufacturer of the blood culture vials. As a consequence of this shortcoming, one manufacturer recently developed an automatic blood volume monitoring system. In conclusion, clear recommendations for standardized blood culture collection combined with quality control of critical factors of the preanalytical phase are essential for diagnostic blood culture improvement.

Prevalence and mechanisms of resistance to carbapenems in Enterobacteriaceae isolates from 24 hospitals in Belgium.

OBJECTIVES To determine the point prevalence of carbapenem-non-susceptible Enterobacteriaceae (CNSE) and carbapenemase-producing Enterobacteriaceae (CPE) isolates among hospitalized patients in Belgium. METHODS Twenty-four hospital-based laboratories prospectively collected 200 non-duplicated Enterobacteriaceae isolates from clinical specimens of hospitalized patients over a 2 month period. All isolates were screened locally for decreased susceptibility to carbapenem drugs using a disc diffusion method according to CLSI interpretative criteria. CNSE strains were referred centrally for confirmation of carbapenemase by phenotypic and molecular testing. RESULTS From February to April 2012, 158 of the 4564 screened Enterobacteriaceae isolates were categorized as non-susceptible to carbapenems, resulting in a point prevalence of CNSE of 3.5% (95% CI: 2.9%-4.2%; range per centre: 0.5%-8.5%). Of the 125 referred CNSE isolates, 11 Klebsiella pneumoniae isolates [OXA-48 (n = 7), KPC type (n = 3) and NDM type (n = 1)], 1 OXA-48-positive Escherichia coli isolate and 1 KPC-positive Klebsiella oxytoca isolate were detected in eight hospitals. None of the 72 carbapenem-non-susceptible Enterobacter spp. isolates were confirmed as CPE. The minimal estimated point prevalence of CPE isolates was 0.28% (13/4564; 95% CI: 0.13%-0.44%) overall (range per centre: 0%-1.5%). CONCLUSIONS Despite the overall low prevalence of CNSE found in this study, the detection of CPE isolates in one-third of the participating centres raises concerns and highly suggests the spread and establishment of CPE in Belgian hospitals.

Performance of a New Chromogenic Medium, BBL CHROMagar MRSA II (BD), for Detection of Methicillin-Resistant Staphylococcus aureus in Screening Samples

ABSTRACT Two chromogenic media for the detection of MRSA were compared: BBL CHROMagar MRSA II (BD) and MRSA ID agar (bioMérieux). Following overnight nonselective enrichment, 1,919 screening samples were inoculated on both chromogenic agars. After 24 h, the sensitivities of both media were high and comparable. Both media showed an important decrease in specificity after 48 h of incubation (decreases of 8% for MRSA II and 10% for MRSA ID), but MRSA II was significantly more specific at both time points.

STREPTOBACILLUS MONILIFORMIS: CASE REPORT AND REVIEW OF THE LITERATURE

Abstract Streptobacillus moniliformis is one of the causes of rat bite fever. The clinical and microbiological diagnosis of this rare infectious disease is often quite problematic. Penicillin, in sufficiently high dosis, is the treatment of choice and leads to a prompt resolution of the infection, whereas lack of treatment leads to a 13% mortality rate. As far as we know, this paper reports the first human isolate in Belgium.

Antimicrobial susceptibility of group B streptococci collected in two Belgian hospitals.

Abstract Objective: to determine the in vitro susceptibility of group B Streptococci(GBS) to antibiotics, used for intrapartum chemoprophylaxis and treatment of infections; to determine the rate of resistance to erythromycin and clindamycin and the phenotype distribution of GBS strains investigated. Methods: 262 GBS strains from pregnant women at 35–37 weeks’ gestation were collected in University Hospital Gasthuisberg (Leuven) and Imelda Hospital (Bonheiden). The minimum inhibitory concentrations (MICs) of penicillin G, amoxicilllin, cefazolin, cefotaxime, erythromycin, clindamycin, gentamicin, vancomycin and linezolid were determined by the agar dilution method, according to NCCLS guidelines. Results: all isolates were susceptible to penicillin, amoxicillin, cefazolin, cefotaxime, vancomycin and linezolid. We found resistance rates of 16.7 % to erythromycin and 11.0 % to clindamycin. Of all erythromycin- resistant strains, 63.6 % had the cMLSB phenotype, 20.5 % the iMLSB phenotype and 15.9 % the M-phenotype. For 25 % of erythromycin-resistant strains, the resistance was of a very high level (MICs ranging from 128 μg/mL to 256 μg/mL). All these isolates belong to the cMLSB phenotype. For the remaining 75 % the resistance to erythromycin was of low level (MICs ranging from 1 μg/mL to 4 μg/mL). These isolates had the cMLSB phenotype (38.6 %), the iMLSB phenotype (20.5 %) and the M-phenotype (15.9 %). Conclusion: the susceptibility of GBS to the β-lactam antibiotics supports the continued use of penicillin for intrapartum chemoprophylaxis. For women who are allergic to penicillin, clindamycin or erythromycin are considered to be the alternatives, however resistance rates to these antibiotics are significant.

Optimisation of Prenatal Group B Streptococcal Screening

The purpose of the study presented here was to confirm the high yield of group B streptococci (GBS) on Granada medium for the detection of pregnant GBS carriers and to compare the results with those obtained using standard Columbia blood agar at two participating centers in Belgium. Culture results of the vaginorectal swabs obtained at the two centers were also compared. A total of 1,142 samples (838 in Leuven and 304 in Bonheiden) obtained from consecutive pregnant women were cultured onto both media. Of all GBS carriers 84.7% were detected on Columbia blood agar and 93.4% on Granada agar (P<0.01, McNemar test). The addition of Granada agar was responsible for a 15% higher rate of detection of GBS carriers. As a result of this study, both participating hospitals will use a combination of Granada agar with Columbia blood agar for optimal GBS screening in the future.

Contamination Management of Broad-Range Ribosomal DNA PCR: Where Is the Evidence?

We have read with great interest the minireview of Millar and colleagues concerning the risk of contamination of broad-range ribosomal DNA (rDNA) PCR ([3][1]). We completely agree with the authors that the high sensitivity of broad-range rDNA PCR could lead to false-positive results. As stated by

Surveillance of antibiotic resistance in non invasive clinical isolates of streptococcus pneumoniae collected in belgium during winters 2003 and 2004.

Abstract A total of 391 and 424 non-invasive isolates of Streptococcus pneumoniae collected by 15 laboratories during the 2003 and 2004 survey were tested for their susceptibility by a microdilution technique following NCCLS recommendations. Insusceptibility rates (IR) in the two surveys (2003/2004) were as follows: penicillin 15.0/14.7 % [8.4/6.4 % Resistance (R)], ampicillin 17.4/14.6 % (R 9.0/7.1 %), amoxicillin ± clavulanic acid 2.6/1.2 % (R 0/0 %), cefaclor 14.3/14.1 % (R 11.5/13.4 %), cefuroxime 13.6/12.7 % (R 10.5/11.8 %), cefuroxime-axetil 10.5/11.8 % (R 10.0/9.2 %) (breakpoints based on 250 mg), cefotaxime 4.9/6.2 % (R 1.3/2.4 %), ceftazidime NotTested (NT)/6.4 (R NT/2.6 %), cefepime NT/6.4 (R NT/2.6 %), imipenem 7.7/8.9 % (R 1.8/1.4 %), ertapenem 0.8/NT % (R 0/NT %), ciprofloxacin 13.8/9.0 % (R 4.3/2.4 %), levofloxacin 3.3/2.8 % (R 1.5/0.2 %), moxifloxacin 0.6/0.2 % (R 0.3/0 %), ofloxacin 13.5/9.0 % (R 4.3/2.4 %), erythromycin 26.1/24.7 % (R 25.3/24.5 %), azithromycin 25.4/24.7 % (R 24.6/24.5 %), telithromycin 0.8/0.2 % (R 0.5/0 %), clindamycin 21.2/18.4 % (R 19.2/17.7 %) and tetracycline 32.3/22.1 % (R 29.2/19.3 %). There were only minor differences in resistance rates according to age, sample site, admission type (i.e. ambulatory, hospitalized or long-term care facility patients), gender and geographic origin. Overall, telithromycin (MIC50, MIC90 in 2003/2004: 0.015 µg/ml, 0.12 µg/ml/ 0.008,0.06 respectively), ertapenem (0.03; 0.25/NT), moxifloxacin (0.06; 0.25/0.06, 0.12), and amoxicillin ± clavulanic acid (0.03; 0.25/0.015, 0.5) were the most active compounds in both surveys. In 2003, the most common resistance phenotype was isolated insusceptibility to tetracycline (10.5 %) followed by combined insusceptibility to erythromycin and tetracycline (9.3 %). Erythromycin-tetracycline resistance (10.4 %) was the most common in 2004. Isolates showing resistance to an antibiotic were significantly more present in 2003 than in 2004 (50.4 % versus 40.8 %). In penicillin-insusceptible isolates, MICs of all beta-lactams were increased but cross-resistance between penicillin and other β-lactams in the penicillin-insusceptible isolates was not complete. In the 2003 survey, most of these isolates remained fully susceptible to ertapenem (94.9 %) and amoxicillin ± clavulanic acid (83.1 %). In the 2004 survey, 91.9 % of the penicillin insusceptible isolates remained susceptible to amoxicillin ± clavulanic acid. In both surveys, the most common serotypes in penicillin insusceptible isolates were 14, 23, 19 and 9 (20.0 %, 20.0 %, 16.4 % and 10.9 % respectively in 2003; 41.6 %, 11.7 %, 15.0 % and 18.3 % respectively in 2004).

10th Survey of antimicrobial resistance in noninvasive clinical isolates of Streptococcus pneumoniae collected in Belgium during winter 2007-2008

OBJECTIVES The aim of the study was to evaluate the antibiotic resistance in noninvasive clinical isolates of Streptococcus pneumoniae collected in Belgium during winter 2008-2007. METHOD Four hundred and forty eight unduplicated isolates collected by 15 laboratories were tested by microdilution following CLSI. RESULTS Insusceptibility rates (I+R) were as follows: penicillin G (PEN) 11.6% (4.0% R), ampicillin 11.4% (4.0% R), amoxicillin+/-clavulanic acid 0, cefaclor 10.3% (9.6% R), cefuroxime 9.2% (8.7% R), cefuroxime-axetil 8.7% (7.8% R), cefotaxime, ceftazidime and cefepime 2.0% (0% R), imipenem 2.5% (0% R), ciprofloxacin and ofloxacin 5.1% (0.4% R), levofloxacin 0.7% (0.4% R), moxifloxacin 0.4% (0.2% R), erythromycin (ERY) 29.7% (29.2% R), azithromycin 29.7% (28.8% R), telithromycin 0%, clindamycin 26.3% (25.4% R) and tetracycline (TET) 21.9% (16.5% R). From 2001 to 2008, a significant decrease in penicillin-insusceptibility (21.0% to 11.6%), penicillin-resistance (9.7% to 4.0%) and ciprofloxacin-insusceptibility (11.2% to 5.1%) was found. Cross-resistance between penicillin and other betalactams in penicillin-insusceptible isolates was incomplete: all these isolates remained fully susceptible to amoxicillin. Erythromycin-insusceptibility was significantly higher in children than in adults (43.9%/27.4%), while penicillin-insusceptibility significantly higher in Brussels than in the Flanders (22.9%/8.1%). The commonest resistance phenotype was ERY-TET (12.7%) followed by ERY (7.4%) and PEN-ERY-TET (5.8%). Capsular types 19 (25%), 14 (19.3%), 23 (15.4%) and 15 (13.5%) were the most important in penicillin-insusceptible. CONCLUSION We noted a decrease in resistance to the majority of the compounds. Insusceptibility rates were higher in children than in adults and the difference between the north and the south of Belgium became less marked.