Prevalence of Plasmid-Mediated Quinolone Resistance Genes and Molecular Typing of Klebsiella pneumoniae Isolates from Blood Cultures in Milad Hospital, Tehran, Iran, Within 2018 - 2019

Plasmid-mediated quinolone resistance (PMQR) determinants are commonly characterized in Klebsiella pneumoniae isolates worldwide and complicate the treatment of infections caused by this bacterium.

This study aimed to investigate the prevalence of PMQR determinants and molecular typing of blood isolates of K. pneumoniae in Milad hospital in Tehran, Iran, within 2018 - 2019.

A total of 100 K. pneumoniae isolates were tested for susceptibility to quinolones using the disk diffusion method. The minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) and levofloxacin (LEV) were determined using the microdilution broth method. The PMQR determinants were detected by polymerase chain reaction (PCR) assay, and the genetic relationship between the isolates was assessed using enterobacterial repetitive intergenic consensus (ERIC)-PCR.

The resistance rates of the isolates to LEV, CIP, nalidixic acid, and norfloxacin were determined to be 62%, 46%, 29%, and 23%, respectively. Eighty-one isolates were resistant to at least one tested quinolone. A high-level CIP and LEV resistance (MIC > 32 mg/L) was observed in 15 (18.51%) and 36 (44.44%) isolates, respectively. The PMQR genes were detected in 71 (87.65%) isolates. The oqxAB, qnrS, qnrD, qnrB, aac(6')-Ib-cr, qnrA, qepA, and qnrC genes were detected in 71 (87.65%), 30 (37%), 25 (30.8%), 24 (29.6%), 18 (22.2%), 17 (21%), 17 (21%), and 8 (9.9%) isolates, respectively. The ERIC-PCR revealed 64 genotypes among quinolone-resistant isolates.

The high prevalence of PMQR genes observed in this study is a significant concern for public health since they can contribute to the spread of fluoroquinolone resistance among clinical isolates. The ERIC-PCR revealed high heterogeneity among the studied isolates, indicating that they emerged from different sources.