Clonal Dissemination of a Multidrug-Resistant Strain of Klebsiella pneumoniae Producing OXA-48 Carbapenemase at a Tunisian Hospital

Harchay, C, Battikh, H , Fendri, C

Emergence and dissemination of carbapenem resistance among Enterobacteriaceae represent a significant threat to the management of nosocomial infections. Klebsiella pneumoniae had proved to be the most concerned as multidrug-resistant bacteria causing severe infections with limited treatment options. In the present study, we investigate the molecular epidemiology of 21 ertapenem-resistant strains of Klebsiella pneumoniae collected in Rabta hospital of Tunisia, between June 2010 and December 2011. The molecular  epidemiology including the characterization of carbapenemases and others β-lactamases, pulsed-field gel electrophoresis, were carried out. Medicals records were reviewed to evaluate predictive factors for infection. All strains were multidrug resistant. The OXA-48 carbapenemase was identified in all strains and was associated with CTX-M-15 and CTX-M-14/CMY-4 in 11 and 1 cases, respectively. Pulsed-field gel electrophoresis typing indicated the clonal dissemination of an epidemic strain. The risk factors for acquired OXA-48 infections were: severity of underlying disease, longer length hospital stay and admission to an intensive care unit. Amplification of antibiotic resistance with expression of carbapenemase and extended-spectrum β-lactamase in the same strain requires continuous surveillance programs using molecular techniques as powerful tools for early detection and for prevention of dissemination of these pan-drug-resistant isolates.