Use of Automated Repetitive-sequence-based PCR for Rapid Laboratory Confirmation of Nosocomial Outbreaks

Objective: Rapid and reliable diagnosis of genetic relatedness of clinical isolates in microbiologic laboratory is essential in case of nosocomial outbreak investigation. Most molecular techniques used to type microorganisms are technically demanding and time consuming. Currently repetitive-sequence-based PCR (rep-PCR) technique has been adapted to an automated format on the DiversiLab system (bioMérieux, Marcy l'Etoile, France). Aim of this study was to compare the performance of the DiversiLab system to that of pulsed-field gel electrophoresis (PFGE) in nosocomial outbreaks.

Methods: 122 clinical isolates (28 Methicillin-resistant Staphylococcus aureus (MRSA), 26 Acinetobacter baumannii, 45 extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae and 13 ESBL-producing Klebsiella oxytoca) were investigated. 70 isolates originated from six well-documented outbreaks, 52 were non-outbreak isolates.

Results: Concordant results for identification of outbreak and non-outbreak MRSA, A. baumannii and ESBL-producing K. pneumoniae strains were achieved with both methods. In the outbreak of ESBL-producing K. oxytoca automated rep-PCR was slightly more discriminatory than PFGE. Rep-PCR identified investigated ESBL-producing K. oxytoca outbreak-strains as indistinguishable or closely related, showing similarity of >90%, while PFGE identified these strains as indistinguishable.

Conclusion: Automated rep-PCR assays on the DiversiLab system were used for MRSA, A. baumannii and for the first time ESBL-producing Klebsiella spp. and proved as a rapid and reliable method for molecular analysis of nosocomial outbreaks.