Abstract:

Fluoroquinolones, are effective agents both against gram-positive and gram-negative bacteria. Quinolones show bactericidal effect as a result of inhibition of DNA gyrase and topoisomerase IV enzymes. Main quinolo resistance mechanisms are chromosomal mutations in these enzymes and decreased intracellular accumulation due to efflux pumps or decreased membrane uptake. Recently a new quinolone resistance mechanism mediated by plasmids has been defined. These plasmids carry genes called as qnr. Qnr genes do not cause quinolone resistance but they cause decreased quinolone susceptibility and lead to higher minimum inhibitory concentrations. Currently there are qnrA, qnrB, qnrC, qnrD and qnrS genes. This study was aimed to investigate the presence of plasmid-mediated quinolone resistance determinants in carbapenem resistant Enterobacterales isolates. A total 154 carbapenem resistant Enterobacterales isolates were included in the study. Presence of qnrA, qnrB, qnrC, qnrD and qnrS genes were investigated by multiplex polymerase chain reaction (PCR) method. The results of the PCR amplification revealed that qnrA was detected in two isolates (E6, E85) (1.29%), qnrB was detected in 12 isolates (8.4%) (E32, E43, E46, E61, E62, E84, E94, E149, E 166, E167, E177, E179) and qnrS was detected in six isolates (E15, E25, E57, E63, E70, E80) (4.54%). And one isolate (E9) was both positive for qnrB and qnrS. QnrC and qnrD were not detected in any isolates. Transferable quinolone resistance due to the dissemination of qnr genes may have important impacts in terms of infection control and treatment problems. Survey of plasmid mediated quinolone resistance will help to determine the size of the issue and guide the measures that should be taken to avoid escalation of resistance and dissemination problem.

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