[The future of automation in bacteriology]. / Automatisation en bactériologie : quel avenir ? Un exemple concret dans le cadre d'une consolidation de laboratoires universitaires.

Bacteriology remained essentially manual for many years. After a partial automation for blood cultures, identifications and sensitivity testing, new technological developments including robotisation and digital pictures made it possible to open new ways. In the context of economic pression and need to increase the quality, automation offers multiple advantages concerning increase of productivity, standardization, traceability and decreasing of the delay to obtain the results. Moreover the use of digitalized pictures opens the way to tele-bacteriology, particularly useful when considering the merging of hospital laboratories because it makes it possible to geographically dissociate strict manipulation from the validation of the results and from the consultant activity of the microbiologist. The choice criteria of the equipment are detailed as well as the experience of the LHUB-ULB bacteriological laboratory which was automated at the time of merging of the Brussels public hospital laboratories and developed a conclusive experience of tele-bacteriology for the peripheral lab.

Accuracy of Automated Flow Cytometry-Based Leukocyte Counts To Rule Out Urinary Tract Infection in Febrile Children: a Prospective Cross-Sectional Study.

Automated flow cytometry of urine remains an incompletely validated method to rule out urinary tract infection (UTI) in children. This cross-sectional analytical study was performed to compare the predictive values of flow cytometry and a dipstick test as initial diagnostic tests for UTI in febrile children and prospectively included 1,106 children (1,247 episodes). Urine culture was used as the gold standard test for diagnosing UTI. The performance of screening tests to diagnose UTI were established using receiver operating characteristic (ROC) analysis. Among these 1,247 febrile episodes, 221 UTIs were diagnosed (17.7% [95% confidence interval {CI}, 15.6 to 19.8%]). The area under the ROC curve for flow cytometry white blood cell (WBC) counts (0.99 [95% CI, 0.98 to 0.99]) was significantly superior to that for red blood cell (0.74 [95% CI, 0.70 to 0.78]) and bacterial counts (0.89 [95% CI, 0.87 to 0.92]) (P < 0.001). Urinary WBC counts also had a significantly higher area under the ROC curve than that of the leukocyte esterase (LE) dipstick (0.92 [95% CI, 0.90 to 0.94]), nitrite dipstick (0.83 [95% CI, 0.80 to 0.87]), or the combination of positive LE and/or nitrite dipstick (0.91 [95% CI, 0.89 to 0.93]) test (P < 0.001). The presence of ≥35 WBC/µl of urine was the best cutoff point, yielding both a high sensitivity (99.5% [95% CI, 99 to 100%]) and an acceptable specificity (80.6% [95% CI, 78 to 83%]). Using this cutoff point would have reduced the number of samples sent to the laboratory for culture by 67%. In conclusion, the determination of urinary WBC counts by flow cytometry provides optimal performance as an initial diagnostic test for UTI in febrile children.

Variations in catheter-related bloodstream infections rates based on local practices.

BACKGROUND: Catheter-related bloodstream infection (CRBSI) surveillance serves as a quality improvement measure that is often used to assess performance. We reviewed the total number of microbiological samples collected in three Belgian intensive care units (ICU) in 2009-2010, and we described variations in CRBSI rates based on two factors: microbiological documentation rate and CRBSI definition which includes clinical criterion for coagulase-negative Staphylococcus (CNS) episode. FINDINGS: CRBSI rates were 2.95, 1.13 and 1.26 per 1,000 estimated catheter-days in ICUs A, B and C, respectively. ICU B cultured fewer microbiological samples and reported the lowest CRBSI rate. ICU C had the highest documentation rate but was assisted by support available from the laboratory for processing single CNS positive blood cultures. With the exclusion of clinical criterion, CRBSI rates would be reduced by 19%, 45% and 0% in ICUs A, B and C, respectively. CONCLUSION: CRBSI rates may be biased by differences of blood culture sampling and CRBSI definition. These observations suggest that comparisons of CRBSI rates in different ICUs remain difficult to interpret without knowledge of local practices.

Group A streptococcus colonies from a single throat swab can have heterogeneous antimicrobial susceptibility patterns.

This study describes for the first time heterogeneity of antibiotic resistance profiles among group A Streptococcus isolates originating from a single throat swab in patients with acute pharyngitis. For each throat swab, 10 group A Streptococcus colonies were randomly selected from the primary plate and subcultured to a secondary plate. These isolates were characterized by various phenotypic and genotypic methods. Our results demonstrated that differing antibiotic resistance profiles were present in 19% of pediatric patients with acute pharyngitis before antimicrobial treatment. This heterogeneity likely resulted from horizontal gene transfer among streptococcal isolates sharing the same genetic background. As only a minority of colonies displayed antibiotic resistance among these heterogeneous samples, a classical diagnostic antibiogram would have classified them in most instances as "susceptible," although therapeutic failure could be caused by the proliferation of resistant strains after initiation of antibiotic treatment.

Incidence and virulence determinants of verocytotoxin-producing Escherichia coli infections in the Brussels-Capital Region, Belgium, in 2008-2010.

The incidence of verocytotoxin-producing Escherichia coli (VTEC) was investigated by PCR in all human stools from Universitair Ziekenhuis Brussel (UZB) and in selected stools from six other hospital laboratories in the Brussels-Capital Region, Belgium, collected between April 2008 and October 2010. The stools selected to be included in this study were those from patients with hemolytic-uremic syndrome (HUS), patients with a history of bloody diarrhea, patients linked to clusters of diarrhea, children up to the age of 6 years, and stools containing macroscopic blood. Verocytotoxin genes (vtx) were detected significantly more frequently in stools from patients with the selected conditions (2.04%) than in unselected stools from UZB (1.20%) (P = 0.001). VTEC was detected most frequently in patients with HUS (35.3%), a history of bloody diarrhea (5.15%), or stools containing macroscopic blood (1.85%). Stools from patients up to the age of 17 years were significantly more frequently vtx positive than those from adult patients between the ages of 18 and 65 years (P = 0.022). Although stools from patients older than 65 years were also more frequently positive for vtx than those from patients between 18 and 65 years, this trend was not significant. VTEC was isolated from 140 (67.9%) vtx-positive stools. One sample yielded two different serotypes; thus, 141 isolates could be characterized. Sixty different O:H serotypes harboring 85 different virulence profiles were identified. Serotypes O157:H7/H- (n = 34), O26:H11/H- (n = 21), O63:H6 (n = 8), O111:H8/H- (n = 7), and O146:H21/H- (n = 6) accounted for 53.9% of isolates. All O157 isolates carried vtx2, eae, and a complete O island 122 (COI-122); 15 also carried vtx1. Non-O157 isolates (n = 107), however, accounted for the bulk (75.9%) of isolates. Fifty-nine (55.1%) isolates were positive for vtx1, 36 (33.6%) were positive for vtx2, and 12 (11.2%) carried both vtx1 and vtx2. Pulsed-field gel electrophoresis revealed wide genetic diversity; however, small clusters of O157, O26, and O63:H6 VTEC that could have been part of unidentified outbreaks were identified. Antimicrobial resistance was observed in 63 (44.7%) isolates, and 34 (24.1%) showed multidrug resistance. Our data show that VTEC infections were not limited to patients with HUS or bloody diarrhea. Clinical laboratories should, therefore, screen all stools for O157 and non-O157 VTEC using selective media and a method for detecting verocytotoxins or vtx genes.

Diagnostic value of five commercial tests for the rapid diagnosis of Clostridium difficile-associated disease.

We compared five commercial immunoassays (Biostar OIA CdTOX AB, ImmunoCard Toxins A&B - Meridian, Xpect C. difficile toxin A/B -Remel, C. difficile toxin A test- Oxoid, and TOX A/B QUIK CHEK- Techlab) which allow a rapid diagnosis of C. difficile associated disease. The tests were performed directly on patient's stool specimen submitted for routine investigation of C. difficile infection from two University Hospitals in Brussels. The cell cytotoxicity assay was considered as the gold standard. Of the 100 stool specimens included in the study 23 were positive for C. difficile toxin. The sensitivity, specificity, positive and negative predictive values were respectively, 95.7%, 100%, 100% and 98.7% for TOX A/B QUIK CHEKTM, 91.3%, 100%, 100% and 97.5% for ImmunoCard Toxins A&B and for Xpect C. difficile toxin A/B, 87%, 100%, 100% and 96.3% for OIA CdTOX AB and 87%, 98.7%, 97.2% and 96.3% for C. difficile toxin A test. The differences were not statistically significant (p > 0.05). These data suggest that the tested immunoassays are acceptable for rapid detection of C. difficile toxin.