Antimicrobial susceptibility testing determined by Alfred 60/AST (Alifax®) in a multi-sites lab: performance's evaluation and optimization of workflow.

PURPOSE: New techniques are needed to speed-up the identification and antimicrobial susceptibility testing (AST) of bacteria associated with bloodstream infections. Alfred 60/AST (Alifax®, Polverara, Italy) performs AST by light scattering directly from positive blood cultures. METHODS: We evaluated Alfred 60/AST performances for 4 months. Each new episode of bacteraemia was included and AST were compared to either our rapid automated AST (Vitek® 2) or disk diffusion method. The discrepancies were investigated using Etest®. The time-to-result (TTR) was evaluated by comparing the blood volume inserted into Alfred 60/AST, i.e. 2 versus 7 blood drops. Taking into account the TTR, the workflow of positive blood cultures and the availability of AST results was studied in order to optimize the implementation of Alfred 60/AST. RESULTS: A total of 249 samples and 1108 antibiotics for AST were tested. After exclusion of unavailable results, 1008 antibiotics were analysed. 94.9% (n = 957/1008) of the antibiotics showed categorical agreement. There were 14 very major errors (VME), 24 major errors (ME) and 13 minor errors (mE). The VME were mostly related to clindamycin (64.3%) whereas meropenem and piperacillin-tazobactam constituted the major part (37.5% and 61.5%) of ME and mE respectively. Results were highly reliable for Enterobacterales and enterococci. The mean TTR ranged between 4.3 and 6.3 h and was statistically 20 min faster when applying the 7 blood drops protocol. We showed that Alfred 60/AST could give relievable results within working hours for positive blood culture which are flagged the same day between 12:00 am and 12:00 pm. CONCLUSION: Our study confirmed that Alfred 60/AST gives reliable AST results in a short period of time, especially for Enterobacterales and enterococci. AST could thus be easily obtained the same day of a positive blood culture. Clinical impact studies are mandatory to validate a 24/24 working.

Staggered enforcement of infection control and prevention measures following four consecutive potential laboratory exposures to imported Brucella melitensis.

From 2015 until 2020, Brucella melitensis was isolated four times in our microbiology laboratory. All patients had travelled in endemic-areas. Immediately after the first occurrence, all laboratory staff were risk-stratified and preventive and protective measures were applied according to CDC guidelines. Nineteen workers were exposed and needed chemoprophylaxis and follow-up. At each subsequent occurrence, risk analysis was performed, and additional measures were implemented accordingly, leading to a progressive reduction of exposed staff members to none the fourth time. We describe here the additional measures that permitted this important exposure reduction.

CT imaging improves histopathological grading of retroperitoneal leiomyosarcomas.

BACKGROUND: Initial grading of retroperitoneal leiomyosarcoma (LMS) is performed by core biopsy (CB) however, discrepancy between grade of tumour at initial CB and surgical excision is recognised, raising concerns about the accuracy of CB for directing neoadjuvant therapy. The histological grading system used for staging LMS consists of 3 components: tumour differentiation, mitotic index and proportion of necrosis. We postulate that assessment of necrosis by histopathology alone is inadequate, resulting in under-grading of LMS. We propose and assess a combined grading system that incorporates CT scan findings into pre-surgical grading. METHODS: Retrospective, blinded review of CT, CB histology and final surgical histology of patients with retroperitoneal LMS was undertaken. A modified grading system, CTH-Grade, was derived by replacing the CB necrosis score with a CT-derived necrosis score. The sensitivity and specificity of CTH-Grade, the standard histopathology scoring, H-grade were compared. Inter-observer variability in assessment of CT necrosis was also assessed. RESULTS: 53 patients fulfilled criteria for inclusion. CT was more sensitive at detection of necrosis than CB histology alone with sensitivity of 100% vs 53%. The use of CTHGrade resulted in increased detection of high-grade tumours with CTH-grade having sensitivities of 80% and 35% for Grade 2 and 3 tumours respectively vs 53% and 15% with H-Grade. Assessment of reader agreement demonstrated Kappa scores of 0.8. CONCLUSION: Histology from CB under-grades LMS due to undersampling of tumour necrosis. CT is more sensitive in assessing necrosis and its incorporation into a modified CT-histopathology grading system (CTH-Grade) improves accuracy of grading with significant implications for patient management.

[Campylobacter jejuni meningitis]. / Méningite à Campylobacter jejuni.

Cases of Campylobacter jejuni meningitis are extremely rare. In the literature, less than ten cases have been described so far, although Campylobacter spp is one of the most common pathogens causing gastroenteritis in the world. Some common stigmata can be found across these cases such as rupture of the blood-brain barrier, immunosuppression, as well as the tropism of Camplylobacter jejuni for neurological parenchyma. Campylobacter jejuni bacteremia is certainly underestimated because Campylobacter is a thermophilic bacterium and special conditions are required to isolate this organism in blood cultures. PCR is thus an interesting alternative technique for diagnosis. In our case, a patient with a history of resected astrocytoma, had undergone treatment with chemotherapy and radiotherapy because of anaplastic transformation. The patient was admitted with gastroenteritis and Campylobacter jejuni meningitis. The diagnosis was obtained initially on stool cultures and then by PCR of cerebrospinal fluid. The evolution was favorable with meropenem.

Les cas de méningite à Campylobacter jejuni restent extrêmement rares. Dans la littérature, on décrit moins de 10 cas à ce jour, alors que l'infection à Campylobacter est cependant l'une des causes les plus répandues de gastro-entérite dans le monde. Le point commun de tous ces cas de méningite rapportés semble être la fragilité de la barrière hémato-encéphalique et l'immunodépression, ainsi que le tropisme du Campylobacter jejuni pour les tissus neuronaux. La bactériémie à Campylobacter jejuni est par ailleurs sous-estimée car le germe est thermophilique et des conditions particulières sont nécessaires pour isoler cet organisme dans les hémocultures. La PCR est une alternative intéressante pour le diagnostic microbiologique. Dans le cas décrit, le patient présentait des antécédents d'astrocytome pariéto-temporal droit opéré, avec une transformation anaplasique ayant bénéficié de chimio- et radiothérapie concomitantes. Le patient a été admis avec une gastro-entérite compliquée d'une méningite à Campylobacter jejuni. Le diagnostic a été posé initialement sur la coproculture et ensuite par la PCR du liquide céphalo-rachidien. L'évolution a été favorable sous méropénem.

Enteropathogens in paediatric gastroenteritis: comparison of routine diagnostic and molecular methods.

OBJECTIVES: Studies of acute gastroenteritis (AGE) are hampered by the lack of routine diagnostic methods with good sensitivity and specificity. Molecular methods are increasingly used for clinical purposes, but the clinical significance of a positive result remains a challenge. In this study we aimed to compare results of routine diagnostic methods and molecular methods in symptomatic children and asymptomatic controls. METHODS: Patients presenting to the pediatric emergency departments of two university hospitals in Brussels with AGE were recruited prospectively from May 2015 to October 2016; asymptomatic controls were recruited from the same hospitals. Stool analyses were performed for all participants for common pathogenic bacteria (culture), virus (immunochromatography) and parasites (microscopy). Stools were also analysed with the Luminex Gastrointestinal Pathogen Panel, a multiplex-PCR for common enteropathogens. RESULTS: Stools from 178 patients and 165 controls were analysed. An enteropathogen was detected in 62.4% (111/178) of cases when combining the two methods (56.2% (100/178) by Luminex, 42.7% (76/178) with routine methods) and 29.1% (48/165) of controls (24.2% (40/165) by Luminex and 10.3% (17/165) by routine methods). Some pathogens were detected more often with Luminex than with routine methods, such as Salmonella (16.3% (29/178) with Luminex and 3.9% (7/178) with routine method, p < 0.05), whereas others identified by culture methods, such as Campylobacter, Shigella, Yersinia, were missed by Luminex. CONCLUSIONS: Molecular tools seem attractive methods, providing high positivity and a rapid turn-around time for the diagnosis of AGE. However, high rates of positivity in both cases and controls highlight the difficulty in interpreting results. Pathogens missed by Luminex but detected by culture methods raise more questions about the true clinical interest of the technique for our patients.

Contribution of the FilmArray Respiratory Panel in the management of adult and pediatric patients attending the emergency room during 2015-2016 influenza epidemics: An interventional study.

AIM: To evaluate the contribution of a multiplex PCR for respiratory viruses on antibiotic and antiviral prescription, ancillary test prescription, admission and length of stay of patients. METHODS: Two hundred ninety-one adult and pediatric patients visiting the emergency department during the 2015-2016 influenza epidemic were prospectively included and immediately tested 24/7 using the FilmArray Respiratory Panel. The results were communicated to the practitioner in charge as soon as they became available. Clinical and biological data were gathered and analyzed. FINDINGS: Results from the FilmArray Respiratory Panel do not appear to impact admission or antibiotic prescription, with the exception of a lower admission rate for children who tested positive for influenza B. Parameters that account for the clinical decisions evaluated are CRP level, white blood cell count, suspected or proven bacterial infection and, for adult patients only, signs of respiratory distress. Length of stay is also not significantly different between patients with a positive and a negative result. A rapid influenza test result permits a more appropriate prescription of oseltamivir.

Prospective evaluation of diagnostic tools for respiratory viruses in children and adults.

AIM: To compare the performances of molecular and non-molecular tests to diagnose respiratory viral infections and to evaluate the pros and contras of each technique. METHODS: Two hundred ninety-nine respiratory samples were prospectively explored using multiplex molecular techniques (FilmArray Respiratory Panel, Clart Pneumovir), immunological techniques (direct fluorescent assay, lateral flow chromatography) and cell cultures. FINDINGS: Molecular techniques permitted the recovery of up to 50% more respiratory pathogens in comparison to non-molecular methods. FilmArray detected at least 30% more pathogens than Clart Pneumovir which could be explained by the differences in their technical designs. The turnaround time under 2 hours for the FilmArray permitted delivery of results when patients were still in the emergency room.

Relation between broiler and human Campylobacter jejuni strains isolated in Belgium from 2011 to 2013.

AIMS: This study inquires the relationship between Campylobacter jejuni isolated from broiler meat carcasses (n = 97) and human clinical samples (n = 72) in Belgium, from 2011 to 2013. METHODS AND RESULTS: The evaluation of the relation was based on the characteristics determined using multilocus sequence typing (MLST) alone and combined with flagellin gene A restriction fragment length polymorphism (flaA-RFLP) typing, antibiotic microbiological resistance profiling (AMRp), lipooligosaccharide class typing or virulence gene profiling (Vp). Clusters containing both human and broiler meat strains were more common when MLST was used alone, followed by MLST/flaA-RFLP and then by MLST/AMRp. More logical chronologically relations broiler-human were obtained for MLST/flaA-RFLP, then for MLST, and finally for MLST/AMRp: i.e. the isolates would first be detected in the broiler meat and at the same time or later in humans. CONCLUSIONS: In several cases, the C. jejuni strains isolated from the consumed broiler meat and from the campylobacteriosis case had the same profile, according to the used typing methods. The circulating Campylobacter strains appear to have remained the same from 2011 till 2013 in Belgium. SIGNIFICANCE AND IMPACT OF THE STUDY: This study corroborates previously published data from Belgium that suggest a strong correlation between C. jejuni strains isolated from broiler meat and from campylobacteriosis patients.

MALDI-TOF MS contribution to the diagnosis of Campylobacter rectus multiple skull base and brain abscesses.

Campylobacter rectus is rarely associated with invasive infection. Both the isolation and the identification requirements of C. rectus are fastidious, probably contributing to an underestimation of its burden. We report the case of a 66-year-old man who developed several skull base and intracerebral abscesses after dental intervention. Campylobacter rectus was isolated from the brain biopsy. Within 45 minutes of reading the bacterial plate, the strain was accurately identified by MALDI-TOF MS. This rapid identification avoided the extra costs and delays present with 16S rRNA gene sequencing and allowed for a rapid confirmation of the adequacy of the empirical antibiotic treatment.

Antibiotic susceptibility profiles among Campylobacter isolates obtained from international travelers between 2007 and 2014.

Campylobacter infection is a common cause of diarrhea among international travelers. We studied antibiotic resistance patterns among Campylobacter isolates obtained from international travelers according to travel destination. Three collections of isolates obtained from international travelers between 2007 and 2014 (Institute of Tropical Medicine, the "Laboratoire Hospitalier Universitaire de Bruxelles "and the Belgian National Reference Centre for Campylobacter) were used. Isolates were tested for minimal inhibitory concentration (MIC) values (E-test macromethod) for fluoroquinolones, macrolides, tetracyclines, amoxicillin-clavulanic acid, and meropenem. Single isolates from 261 travelers were available; median (IQR) age was 25.4 (4-42) years, 85.8% were symptomatic (information for 224 patients available). Overall resistance to ciprofloxacin was 60.9%, ranging from 50.8% in Africa to 75.0% in Asia. Resistance to erythromycin was 4.6%, with the highest rate observed for Southern Asia (15.2%, seven isolates, six of them recovered from patients returning from India). A total of 126 isolates (48.3%) were resistant to tetracycline. No resistance to amoxicillin-clavulanic acid or meropenem was detected. Ciprofloxacin resistance tended to increase over time (53.9% in 2007 versus 72.2% in 2014), erythromycin resistance remained stable (median annual resistance 4.2%). Most (86.2%) ciprofloxacin-resistant isolates had MIC values ≥32 mg/l, and all erythromycin-resistant isolates had MIC values ≥256 mg/l. Co-resistance to ciprofloxacin and erythromycin was observed in 11 (4.2%) isolates, seven of which came from Southern Asia. Among all regions of travel, more than half of Campylobacter isolates were resistant to ciprofloxacin. Overall resistance to erythromycin was below 5% but reached 15.2% in Southern Asia.

Multicenter Evaluation of the Cepheid Xpert Hepatitis C Virus Viral Load Assay.

Viral load monitoring for hepatitis C virus (HCV) is necessary to diagnose infection and monitor response to therapy, but the tests involved are currently confined to specialist institutions. There is a need for a fast, accurate assay with limited operator input to enhance the access to viral load monitoring. We evaluated the quantification of HCV RNA in serum and plasma by the Cepheid Xpert HCV Viral Load assay in comparison to the Abbott RealTime HCV assay. Serum and plasma samples were gathered from HCV-infected individuals at four international sites. These were tested with the Xpert HCV Viral Load assay, and results were compared to quantification by the Abbott RealTime HCV assay. An external quality assessment panel of eight samples was also tested. In total, 614 samples were analyzed in the study, and the qualitative results agreed on the two platforms for 588 (95.8%) samples. Further analysis of 396 samples quantified by both tests showed strong correlation (correlation coefficient r = 0.99) across the quantifiable range, with Bland-Altman plot data showing a mean difference (±1.96 standard deviation) of 0.03 ± 0.44 log10 IU/ml. In the external quality assessment panel, the Xpert HCV Viral Load assay results (quantified in log10 IU per milliliter) were within 1 standard deviation of the target value for all but one sample, which was also similarly misquantified by the Abbott RealTime HCV assay. The Xpert HCV Viral Load assay performs well compared to a market-leading HCV viral load test and should be considered for instances where rapid near-to-patient testing is required.

Dynamics of nasal carriage of methicillin-resistant Staphylococcus aureus among healthcare workers in a tertiary-care hospital in Peru.

The study aims were to describe the frequency and dynamics of methicillin-resistant Staphylococcus aureus (MRSA) carriage among healthcare workers (HCWs), and to compare the molecular epidemiology of MRSA isolates from HCWs with those from patients with bacteremia. HCWs were interviewed and three nasal swabs were collected in a hospital in Lima, Peru, during 2009-2010. Consecutive S. aureus blood culture isolates from patients with bacteremia in the same hospital were also collected. SCCmec, multilocus sequence typing (MLST), and spa typing were performed. Persistent carriage was defined if having at least two consecutive cultures grown with S. aureus harboring an identical spa type. Among 172 HCWs included, the proportions of S. aureus and MRSA nasal carriage during first sampling were 22.7 % and 8.7 %, respectively. From 160 HCWs who were sampled three times, 12.5 % (20/160) were persistent S. aureus carriers and 26.9 % (43/160) were intermittent carriers. MRSA carriage among persistent and intermittent S. aureus carriers was 45.0 % (9/20) and 37.2 % (16/43), respectively. Fifty-six S. aureus blood culture isolates were analyzed, and 50 % (n = 28) were MRSA. Multidrug resistant ST5-spa t149-SCCmec I and ST72-spa t148-SCCmec non-typeable were the two most frequent genotypes detected among HCWs (91.7 %, i.e., 22/24 HCW in whom MRSA was isolated in at least one sample) and patients (24/28, 85.7 %). In conclusion, we found high proportions of MRSA among persistent and intermittent S. aureus nasal carriers among HCWs in a hospital in Lima. They belonged to similar genetic lineages as those recovered from patients with bacteremia.

Staphylococcus aureus nasal carriage among healthcare workers in Kisangani, the Democratic Republic of the Congo.

Methicillin-resistant Staphylococcus aureus (MRSA) is a global health concern, but there are few data from Central Africa. The objective of our study was to characterise S. aureus colonisation isolates from healthcare-exposed professionals in the Democratic Republic of the Congo (DRC). Healthcare workers and medical students (n = 380) in Kisangani, DRC were screened for S. aureus nasal carriage in a single-centre cross-sectional study in the University Hospital of Kisangani. The isolates were identified and characterised using phenotypic and genotypic methods. The nasal carriage rate of S. aureus was 16.6 % and 10 out of 63 isolates (15.9 %) were MRSA. We found 28 different spa types. Most MRSA isolates belonged to ST8-spa t1476-SCCmec V. The majority of MRSA were multidrug-resistant to non-beta-lactam antibiotics. Overall, 28.5 % of S. aureus carried Panton-Valentine leucocidin (PVL)-encoding genes (all methicillin-sensitive) and 17.5 % carried toxic shock syndrome toxin-1 (TSST-1)-encoding genes. The finding of MRSA carriage among healthcare workers in a setting with limited access to diagnostic microbiology and appropriate therapy calls for improved education on infection control practices and supports the introduction of surveillance programmes.

Dynamic pattern and genotypic diversity of Staphylococcus aureus nasopharyngeal carriage in healthy pre-school children.

OBJECTIVES: It is common wisdom that persistent carriage of Staphylococcus aureus is more frequent in young children than in adults. The objectives of this study were to assess the S. aureus temporal carriage pattern among a healthy community of pre-school children, with concomitant description of genotype diversity, toxin-encoding genes and antibiotic resistance. METHODS: Among 333 children 3-6 years of age, S. aureus nasopharyngeal carriage was assessed over one school year by culture of three sequential nasopharyngeal aspirates. Identification, methicillin resistance and toxin production profile were determined by PCR. Genotyping was performed by spa sequencing and multilocus sequence typing (MLST). RESULTS: Out of 830 samples collected, 286 (34%) yielded S. aureus from 185 carriers (55%). Based on consecutive genotype analysis, only 40/268 (15%) children could be classified as persistent carriers, and the remaining 118 (44%) showed intermittent carriage. spa typing revealed 82 types clustered into 13 spa clonal complexes (CCs). Fourteen strains isolated from 11 (3%) children were methicillin-resistant S. aureus (MRSA), half of these strains belonged to the commonly hospital-associated spa t008-ST8-SCCmec IV. Methicillin-susceptible S. aureus (MSSA) were genotypically more diverse. Toxic shock syndrome toxin and egc1/2 complexes were highly prevalent (24%). Contrastingly, Panton-Valentine leucocidin (PVL) was carried only by three MSSA strains (0.6% of children). Exfoliative toxins were detected in 10 (3.5%) MSSA strains, of which 5 were related to the impetigo clone CC121. CONCLUSIONS: Although S. aureus nasopharyngeal carriage was high among healthy pre-school children, persistent carriage seems to be less frequent than previously reported. The prevalence of MRSA carriage was 3%, but was not associated with PVL.

Comparative epidemiology of Staphylococcus epidermidis isolates from patients with catheter-related bacteremia and from healthy volunteers.

Staphylococcus epidermidis is a major cause of catheter-related bloodstream infections (CRBSIs). Recent studies suggested the existence of well-adapted, highly resistant, hospital-associated S. epidermidis clones. The molecular epidemiology of S. epidermidis in Belgian hospitals and the Belgian community has not been explored yet. We compared a set of 33 S. epidermidis isolates causing CRBSI in hospitalized patients with a set of 33 commensal S. epidermidis isolates. The factors analyzed included resistance to antibiotics and genetic diversity as determined by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and SCCmec typing. Additionally, the presence of virulence-associated mobile genetic elements, the ica operon and the arginine catabolic mobile element (ACME), was assessed and compared against clinical data. CRBSI S. epidermidis isolates were significantly resistant to more antibiotics than commensal S. epidermidis isolates. The two populations studied were very diverse and genetically distinct as only 23% of the 37 PFGE types observed were harbored by both CRBSI and commensal isolates. ACME was found in 76% of S. epidermidis strains, regardless of their origin, while the ica operon was significantly more prevalent in CRBSI isolates than in commensal isolates (P < 0.05). Nine patients presented a clinically severe CRBSI, eight cases of which were due to an ica-positive multiresistant isolate belonging to sequence type 2 (ST2) or ST54. S. epidermidis isolates causing CRBSI were more resistant and more often ica positive than commensal S. epidermidis isolates, which were genetically heterogeneous and susceptible to the majority of antibiotics tested. Clinically severe CRBSIs were due to isolates belonging to two closely related MLST types, ST2 and ST54.

Community-acquired methicillin-resistant Staphylococcus aureus clones circulating in Belgium from 2005 to 2009: changing epidemiology.

The present study reports the evolution of the demographic characteristics and the molecular epidemiology of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in Belgium from 2005 to 2009. Four hundred and ten CA-MRSA isolates were prospectively collected and screened for the presence of Panton-Valentin leucocidin (PVL) and toxic shock syndrome toxin 1 (TSST-1) encoding genes, while clinical information were recorded. PVL- and TSST-1-positive isolates were genotyped by pulsed-field gel electrophoresis (PFGE). Staphylococcal cassette chromosome mec (SCCmec) type, spa type and multilocus sequence type (MLST) were determined on representative isolates. One hundred and fifty-nine (39 %) isolates were PVL-positive. PVL-positive isolates were significantly more frequently isolated from skin or soft tissue than PVL-negative isolates, causing mainly subcutaneous abscesses and furuncles. Patients with PVL-positive CA-MRSA were significantly younger than patients with PVL-negative CA-MRSA. Eighty-seven percent of the PVL-positive isolates belonged to a limited number (n = 7) of PFGE types belonging to sequence types (ST) ST80, ST8, ST30, ST5, ST152, ST338 and a new ST, a single-locus variant of ST1. A temporal evolution of the distribution of these PFGE types was observed, characterised by (1) the dissemination of the ST8-SCCmecIV arcA-positive (USA300) genotype and (2) a genetic diversification. Forty-seven (11 %) strains were TSST-1-positive, of which 65 % clustered into four PFGE types, all belonging to ST5. The epidemiology of CA-MRSA in Belgium is changing, as the rapid diffusion of the USA300 clone seems to occur, together with a clonal diversification.

Previous healthcare exposure is the main antecedent for methicillin-resistant Staphylococcus aureus carriage on hospital admission in Belgium.

This study aimed to estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage upon hospital admission and to study the molecular epidemiology of MRSA in order to assess the proportion of Panton-Valentine leukocidin (PVL)-positive community-associated (CA) and livestock-associated (LA) MRSA strains. Epidemiological data on MRSA carriage upon hospital admission (2006-2009) were collected in a compulsory, continuous, national MRSA surveillance in Belgian acute-care hospitals. Additionally, 328 MRSA strains in 2005 and 314 strains in 2008 were collected in a separate, multicenter microbiological survey. Spa-typing, SCCmec-typing and MLST were performed; toxin genes were detected by PCR. The overall prevalence of MRSA carriage upon hospital admission was 8.9 cases/1,000 admissions between 2006 and 2009. Of MRSA carriers, 37.5% had a known MRSA history, 39.4% had stayed in a care facility, 12.2% reported no contact with healthcare. Over 90% of MRSA belonged to five healthcare-associated clones. Of these, MRSA spa-CC038-ST45-IV was in decline, mainly in favor of spa-CC008-ST8-IV. MRSA spa-CC002-ST5-IV, spa-CC002-ST5-II and spa-CC032-ST22-IV remained relatively stable. The proportion of PVL-positive CA-MRSA and LA-MRSA ST398 was below 2% of all MRSA. The extra-hospital MRSA reservoir in Belgium mainly consists of persons with previous healthcare exposure. PVL-positive CA-MRSA and LA-MRSA strains remained infrequent among hospitalized patients.

Pseudo-outbreak of extremely drug-resistant pseudomonas aeruginosa urinary tract infections due to contamination of an automated urine analyzer.

By the end of May 2010, an increase in the number of urine specimens that were culture positive for extremely drug-resistant (XDR) Pseudomonas aeruginosa was observed in our 800-bed university hospital. This led to an infection control alert. No epidemiological link between the patients and no increase in the frequency of XDR P. aeruginosa in non-urine samples were observed. Therefore, a pseudo-outbreak due to analytical contamination in the laboratory was rapidly suspected. A prospective and retrospective search of cases was initiated, and the sampling of the automated urine analyzers used in the laboratory was performed. Antibiotypes were determined by disc diffusion, and genotypes were determined by pulsed-field gel electrophoresis (PFGE). From February to July 2010, 17 patients admitted to 12 different departments and 6 outpatients were included. The mixing device of the cytometric analyzer used for the numeration of urinary particles (Sysmex UF1000i) proved to be heavily contaminated. Isolates recovered from 12 patients belonged to the same antibiotype and PFGE type as the isolate recovered from the analyzer. Extensive disinfection with a broad-spectrum disinfectant and the replacement of the entire tubing was necessary to achieve the complete negativity of culture samples taken from the analyzer. A pseudo-outbreak caused by an XDR P. aeruginosa clone was proven to be due to the contamination of the cytometric analyzer for urinary sediment. Users of such analyzers should be aware that contamination can occur and should always perform culture either before the processing of the urine sample on the analyzer or on a distinct sample tube.