Detection of gyrA ser83 mutation and parC gene amplification in E.coli and Klebsiella pneumoniae from tertiary care hospital, Puducherry

Introduction: Fluoroquinolones are the broad spectrum antibiotics and recently the clinical isolates of Enterobacteriaceae species had slowly extend the high resistance towards them. The point mutation in gyrA gene had showed decreased susceptibility to ciprofloxacin and resistant to nalidixic acid. The aim of the present study was to identify gyrA and parC genes and gyrA ser83 mutation among clinical isolates of Escherichia coli and Klebsiella pneumoniae by RFLP. Methods: A total of 100 clinical strains of both Escherichia coli and Klebsiella pneumoniae were collected from tertiary care hospital from Pondicherry. All the strains were subjected to antimicrobial susceptibility pattern testing by disc diffusion method as per the Clinical Laboratory Standard Institute (CLSI2012). PCR based screening of gyrA and parC was carried out and additional analysis of gyrA ser83-phe mutation in E.coli and K.pneumoniae by agarose gel electrophoresis. Results: Variation in both ciprofloxacin and nalidixic acid resistance were showed in the (100) clinical isolates of E.coli and K. pneumoniae were reported earlier. GyrA and parC genes were detected in both susceptible and resistant isolates of E.coli and K.pneumoniae. Among them, E.coli showed 100% (50/50) and K.pneumoniae showed 84% (42/50) positivity for gyrA while 78% (39/50) and 64% (32/50) positivity for parC. PCR-RFLP results indicated gyrA ser83 mutation in 84% (42/50) of E.coli and 66% (33/50). The results also shows that E.coli is less susceptible to fluoroquinolones compared to K.pneumoniae. Conclusion: The overall resistance were increased for the ciprofloxacin and nalidixic acid among clinical isolates of E.coli and K. pneumoniae due to gyrA ser83-phe mutation. The antimicrobial resistance to fluoroquinolone drugs indicate the rapid genetic modifications undertaken by Enterobacteriaceae species and need for routine screening for resistance to develop next generation drugs.