Nosocomial dissemination of Providencia stuartii isolates carrying blaOXA-48, blaPER-1, blaCMY-4 and qnrA6 in a Tunisian hospital

Methods: Eight intensive care unit (ICU) patients infected/colonized by extended-spectrum b-lactamase (ESBL)-producing P. stuartii between March and May 2011 were included. Molecular epidemiology was studied by PFGE. Antibiotic resistance genes were analysed by PCR and sequencing and the plasmid incompati-bility group by a PCR-based replicon typing scheme. Results: Eight patients were colonized with ESBL-producing P. stuartii isolates. All these isolates were clonally related and found to carry blaOXA-48, blaPER-1, blaCMY-4, qnrA6 and aac-6′-Ib genes on the same self-conjugative IncA/C plasmid. The same strain was also cultured from environmental samples in the ICU. All these isolates were susceptible to carbapenems. Only one colonized patient developed P. stuartii pleurisy and was effectively treated with imipenem alone. Conclusions: This is the first report of an outbreak due to P. stuartii isolates carrying blaOXA-48 in Tunisia. The simultaneous expression of various resistance genes (blaOXA-48, blaCMY-4, blaPER-1, qnrA and aac-6′-Ib) by P. stuartii isolates is alarming