Study of mutations in the quinolone resistance determinant regions of gyrA and parC among clinical isolates of Escherichia coli

Background and Aim : Extensive consumption of quinolones and fluoroquinolones in the urinary tract infections (UTIs) have led to the increasing rate of resistance to these drugs. Occurrence of mutations in the QRDR region in the gyrA and parC genes encoding the target enzymes for fluroquinolones is the reason for resistance to them. The purpose of this study was conducted to determine the antibiotic resistance profile and mutations occurred in gyrA and parC genes among Escherichia coli (E. coli) isolates causing UTIs. Methods : One-hundred E. coli isolates causing UTIs were obtained for the study. The isolates were identified following standard microbiology procedures as described everywhere. The antibiotic resistance profile was done according to the clinical laboratory standards institute (CLSI) protocol. Next, the quinolone-resistant isolates were evaluated regarding the mutations in the gyrA and parC genes with sequence analysis. Results : of the total ۱۰۰ isolates, ۶۶% and ۲۷.۴% were resistant to nalidixic acid and ciprofloxacin, respectively. The sequencing results showed the presence of at least one mutation in each isolate, by occurrence of ۸۳ (Ser Leu), ۸۷ (Asp Asn) in gyrA gene and ۸۰ (Ser Leu/Arg) and ۸۴ (Glu Lys/Gly) in the parC gene as the main mutations detected here. Conclusion : results from sequencing of gyrA and parC genes in the present study highlights the occurrence of those mutations leading to the high level resistance to quinolones and there was a significant relation between resistance to quinolones and these mutations. In order to overcome this issue, there is a need for restriction of indiscriminate prescribing antibiotics and performance and following the antibiotic susceptibility pattern of infectious agents.

کلیدواژه ها:

Escherichia coli ، gyrA ، parC ، urinary tract infections ، quinolones ، fluroquinolones