[Extra-digestive reservoir of extended-spectrum beta-lactamase producing Enterobacteriaceae in non-infected patients: a study based on the systematic searching in urine and other clinical samples].

Our objective was to assess the extra-digestive reservoir of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBLE) by identifying them in clinical samples in which growing bacteria are not systematically analysed (bacterial identification and antimicrobial susceptibility testing) in routine practice. During a 5-week period, an analysis was systematically performed for Enterobacteriaceae colonies isolated in certain clinical samples (urine samples, respiratory-tract samples, and a group of samples called "miscellaneous samples") according to our study protocol. Samples in which an antimicrobial susceptibility testing was performed for bacteria isolated according to our routine practice were considered infected. Samples in which ESBLE were sought and isolated according to the study protocol were considered colonised. During the study, 2312 urine samples, 327 respiratory-tract samples, and 1887 miscellaneous samples were addressed to the laboratory. Among the 114 urine samples colonised with Enterobacteriaceae, 13 (11.4%) grew with ESBLE whereas this proportion was 5.1% (35/682) in infected US (P<0.01). Among respiratory-tract and miscellaneous samples, 3 ESBLE were isolated in the 55 samples colonised with at least one Enterobacteriaceae. Overall, the systematic searching of ESBLE in the clinical samples provided a 27.7% increase of the patients identified as carriers in the entire hospital during the study period. Further studies would be useful to evaluate the interest of using such a strategy instead of systematic rectal screening.