Clonality of Providencia stuartii isolates involved in outbreak that occurred in a burn unit

In order to investigate an outbreak of multidrug-resistant Providencia stuartii that occurred in a burn unit, we analyzed by pulsed-field gel electrophoresis (PFGE) all isolates of P. stuartii collected during 4 months of 2005 from patients and from a tracheal aspirator. Seventeen clinical isolates of P. stuartii, extended-spectrum beta-lactamase (ESBL) producing, were collected from 17 patients. All these isolates were nosocomially acquired. Three other isolates were collected from the aspirator probe, the aspirator reservoir and from the aspirator tube. Three different antibiotypes were identified without correlation with the genotype. Two PFGE types were obtained (types A and B) with predominance of one (type A) that was observed for 15 isolates. P. stuartii isolates collected from different components of the aspirator (probe, reservoir and tube) yielded PFGE type A. This study suggests the bi-clonality of the outbreak and that transmission of epidemic P. stuartii isolates was through a common source. The aspirator probe, contaminated from aspirator that functioned as a reservoir of bacteria, seems to be the route of transmission of P. stuartii. Furthermore, this study shows the utility of PFGE in typing for the purpose of understanding the epidemiological behaviour of P. stuartii and as a basis for the development of rational control strategies.