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Mutation patterns in gyrA and parC genes of ciprofloxacin resistant isolates of Neisseria gonorrhoeae from India
  1. U Chaudhry1,
  2. K Ray2,
  3. M Bala2,
  4. D Saluja1
  1. 1Dr BR Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007, India
  2. 2Regional STD Laboratory, Safdarjung Hospital, New Delhi, India
  1. Correspondence to:
 Dr Daman Saluja, 8/5, Block #41, Singh Sabha Road, Delhi-110007, India;
 dsalujach{at}yahoo.com

Abstract

Aim: To analyse mutations in the gyrA and parC genes leading to possible increase in ciprofloxacin resistance (high MIC values for ciprofloxacin) in clinical isolates of Neisseria gonorrhoeae in Delhi, India.

Method: MIC of ciprofloxacin for 63 clinical isolates of N gonorrhoeae were examined by the Etest method. Subsequently, gyrA and parC genes of these isolates were amplified and sequenced for possible mutations.

Results: Out of the 63 clinical isolates tested, only five (8%) isolates were found to be susceptible to ciprofloxacin (MIC <0.06 μg/ml). DNA sequence analysis of the gyrA and the parC genes of all these isolates (n = 63) revealed that all isolates which were not susceptible to ciprofloxacin (n=58) had mutation(s) in gyrA and parC genes. 12 isolates (19%) exhibited high resistance with an MIC for ciprofloxacin of 32 μg/ml. Two out of these 12 isolates (UD62 and UD63), harboured triple mutations (Ser-91 to Phe, Asp-95 to Asn and Val-120 to Leu) in the gyrA gene. The third mutation of Val-120 to Leu, lies downstream of the quinolone resistance determining region (QRDR) of the gyrA and has not been described before in gonococcus. In addition, both these isolates had a Phe-100 to Tyr substitution in the parC, a hitherto unknown mutation.

Conclusions: Emergence of ciprofloxacin resistance with high levels of MIC values (up to 32 μg/ml) in India is alarming. Double and triple mutations in gyrA alone or together in gyrA and parC could be responsible for such a high resistance.

  • ciprofloxacin
  • Neisseria gonorrhoeae
  • novel mutations
  • gyrA gene
  • parC gene
  • India
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