Study of Amino Acid Alteration in graA & parC Genes in Quinolone Resistant Klebsiella pnemoniae

Fluoroquinolones are broad spectrum antibiotics which targets DNA gyrase and topoisomerase IV and prevents bacterial DNA replication and transcription. We aimed to determine amino acid alterations in garA and parC genes in quinolone resistant Klebsiella pnemoniae isolated from urinary tract infections in Rasht, Iran.
A total of 68 K. pneumoniae strains were isolated from urinary tract infections in Rasht, Iran, Resistance of K. pneumoniae to ciprofloxacin and the MIC of ciprofloxacin were determined according to the Clinical and Laboratory Standard Institute (CLSI) guideline. Quinolone resistance determining regions (QRDRs) of gyrA and parC were amplified in polymerase chain reaction (PCR) and subsequently sequenced. The changes in base and amino acid sequences were compared to the standard strain of K. pneumoniae in the GeneBank.
Out of 68 K. pneumoniae clinical isolates, 16 isolates (23.5%) were phenotypically resistant to ciprofloxacin antibiotic, and 10 isolates (14.7%) had high levels of resistance. Investigation of the sequence of gyrA showed that in 7 out of 10 isolates, the mutation results in the substitution of an amino acid. Double mutation of Ser83Pheˊ糬ग़ and Ser83Pheˊ糬ଧ were the most common. In 4 out of 10 strains, the mutation in parC led to substitution of serine to isoleucine at codon 80.
Obtained results showed the high distribution of mutation hotspots in gyrA and parC in local isolates of K. pneumoniae.