Fluoroquinolone resistance and mutation in gyrA gene in clinical isolates of Klebsiella pnemoniae

Background and Aim: Fluoroquinolone resistance has been mainly associated with mutation in gyr and par genes bacteria and specific amino acids alteration in gram negative bacteria. In the present study, urinary tract infection isolates of Klebsiella pneumonia were investigated for fluoroquinolone resistance and mutation patterns of gyrA gene in ciprofloxacin resistant isolates. Materials and Methods: In ۲۰۱۴, Susceptibility to fluoroquinolones in ۴۶ isolates of K. pneumoniae was tested by the disc diffusion method whereas broth macrodilution method was used to investigate ciprofloxacin minimum inhibitory concentration. Mutations in the quinolone resistance-determining regions (QRDR) was investigated in chromosomal gyrA gene in quinolone-resistant K. pnemoniae isolates, by PCR amplification of gyrA gene and sequencing. Results: Out of ۴۶ tested bacteria, ten (۲۱.۷%) isolates recognized as fluoroquinolones resistant. Minimum inhibitory concentration of ciprofloxacin for resistant isolates ranged between ۶۴ to ۲۰۴۸ µg/mL. In gyrA gene sequence analyses, ۸ (۸۰%) isolates had an amino acid substitution. In six isolates mutation occurred in Asp۸۷ that amino acid alters with Alanine and asparagine. Also Ser۸۳Ile substitution was found in one isolate. Conclusions: The obtained results demonstrated that gyrA mutation is one of the most important mechanisms of resistance to ciprofloxacin in clinical isolates of K. pneumonia in Rasht.

کلیدواژه ها:

Klebsiella pnemoniae ، Fluoroquinolone resistance ، gyrA ، کلبسیلا پنومونیه ، مقاومت به فلورکینولون ، ژن gyrA