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

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 Iraqi isolates toward quinolone antimicrobial agents, to determine genetic mutations in and , to screen for efflux-pump activity, and to screen the presence of plasmid-mediated quinolone resistance (PMQR) genes. Forty-three isolates were confirmed phenotypically and genotypically by Vitek 2 system and species specific primers by PCR using the targeting 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 , and was tested by PCR. Sequencing of A and C was performed. 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 A that was observed in all quinolone resistant isolates, followed by Asp87Asn. Ser80Ile mutation in C was observed in 77.7% of the tested isolates. The prevalence of PMQR genes was 92.5% , 51.8% B, 40.7% A, and 37% S. Quinolone resistance is common in isolates in Baghdad. The frequent mutation in A and C, and the presence of PMQR genes is alarming.