Coexistence of blaOXA-48 and aac(6')-Ib-cr genes in Klebsiella pneumoniae isolates from Istanbul, Turkey

This study evaluated the presence of carbapenem hydrolysing β-lactamase genes and plasmid-mediated quinolone resistance (PMQR) determinants in 22 Klebsiella pneumoniae isolates collected from the Istanbul Medical Faculty, Turkey, which reduced the susceptibility or resistance to carbapenem. The VITEK(®) 2 system and E-tests were used to determine the minimum inhibitory concentrations needed to inhibit bacterial growth. Genes were screened by polymerase chain reaction, and gene transferability was evaluated by transconjugation. Strain clonality was investigated by pulsed-field gel electrophoresis (PFGE). All strains were OXA-48 β-lactamase producers and three (13.6%) were also positive for the aac(6')-Ib-cr gene. Most of the strains harboured other β-lactamase (bla) genes such as bla(TEM), bla(SHV), bla(CTX-M) and bla(VEB-1). The transconjugants mostly harboured bla(OXA-48) and other β-lactamases separately. PFGE revealed eight pulsotypes among the isolates. The coexistence of bla(OXA-48) and PMQR in K. pneumoniae isolates may present a significant threat to health, especially in the nosocomial setting.