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

ABSTRACT: 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.

SUBMITTER: Hallin M

PROVIDER: S-EPMC3295159 | biostudies-other | 2012 Mar

REPOSITORIES: biostudies-other

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

Hallin M M Deplano A A Roisin S S Boyart V V De Ryck R R Nonhoff C C Byl B B Glupczynski Y Y Denis O O

Journal of clinical microbiology 20120104 3

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 re ...[more]

PMID: 22219304

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Project description:OBJECTIVE:To study 1) whether the accuracy of point-of-care (POC) urine tests (dipstick, phase-contrast microscopy and culture) differs when performed on first-void urine (FVU) compared to mid-stream urine (MSU), and 2) if a delay of analysis up to four hours affects the accuracy of POC tests when performed on urine from symptomatic of urinary tract infection (UTI), non-pregnant women in general practice. DESIGN:Prospective diagnostic study using paired samples. Setting/Intervention: Three general practices in Copenhagen. Each woman delivered FVU and MSU samples from the same void. As a reference standard, 8?ml of MSU was sent for culture at the Microbiology Department. PATIENTS:117 women with one or more symptoms of UTI. MAIN OUTCOME MEASURES:Sensitivity, specificity and agreement with the reference standard of FVU and MSU with different time delays (zero vs. one vs. four hours) as compared to reference standard (MSU at time zero in boric acid tubes). RESULTS:All three POC tests performed on MSU were significantly more in agreement with the reference than when performed on FVU when analysis was done immediately. The error rate was 16% for MSU vs. 23% for FVU with POC culture, 27% vs. 40% with microscopy and 25% vs. 33% with dipstick testing. Delay of analysis up to four hours did not decrease agreement with the reference. Conclusion/Implication: MSU samples should be used in general practice for optimal accuracy of POC tests. Analysis can be delayed up to four hours. Key points Point-of-care tests (dipstick testing, microscopy and culture) for diagnosing urinary tract infection performed on mid-stream urine samples are significantly more accurate than when performed on first-void urine samples. Delay of analysis up to four hours did not decrease the accuracy of any of the point-of-care tests. Point-of-care culture was more accurate than dipstick and microscopy both when performed on mid-stream urine and first-void urine The main contaminant in first-void urine samples was Enterococci spp., which contributed to the majority of false positives.

Dataset Information

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

Publications

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

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