Detection of gyrA and parC Mutations and Prevalence of Plasmid-Mediated Quinolone Resistance Genes in Klebsiella pneumoniae

Background and Aim: Recently, the extensive use of quinolones led to increased resistance to these antimicrobial agents, with different rates according to the organism and the geographical region. The aim of this study was to detect the resistance rate of Klebsiella pneumoniae Iraqi isolates toward quinolone antimicrobial agents, to determine genetic mutations in gyrA and parC , to screen for efflux-pump activity, and to screen the presence of plasmid-mediated quinolone resistance (PMQR) genes. Methods: Forty-three K. pneumoniae isolates were confirmed phenotypically and genotypically by Vitek 2 system and species specific primers by PCR using the targeting rpo gene followed by sequencing. Antibiotic susceptibility test was carried out using disc diffusion method. Quinolone resistant isolates were subjected to ciprofloxacin MIC testing, and cartwheel method to screen for efflux pump activity. The presence of the plasmid mediated quinolone resistance genes qepA, qnrB, qnrS , and aac(6)Ib was tested by PCR. Sequencing of gyr A and par C was performed. Results: We observed a high rate of resistance to ceftriaxone, gentamicin ciprofloxacin, and levofloxacin. Low rate of resistance was detected against amikacin and azithromycin. Ciprofloxacin MIC results revealed that 96.1% of the isolates had MICs > 256 μg/mL, 83.4% had MICs > 512 μg/mL while 34.6% had MIC > 1024 μg/mL. Testing of isolates against ciprofloxacin mixed with EtBr at various concentrations resulted in decreased resistant. Sequencing results showed that Ser83Leu was the most common mutation in gyr A that was observed in all quinolone resistant isolates, followed by Asp87Asn. Ser80Ile mutation in par C was observed in 77.7% of the tested isolates. The prevalence of PMQR genes was 92.5% aac (6)-Ib , 51.8% qnr B, 40.7% qep A, and 37% qnr S. Conclusion: Quinolone resistance is common in K. pneumoniae isolates in Baghdad. The frequent mutation in gyr A and par C, and the presence of PMQR genes is alarming. Keywords: MDR K. pneumoniae , quinolones resistance gene, PMQR