Mutation patterns in gyr A and par C genes of ciprofloxacin resistant isolates of Neisseria gonorrhoeae from India

Chaudhry, U
Ray, K
Bala, M
Saluja, D

¹Dr BR Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007, India
²Regional STD Laboratory, Safdarjung Hospital, New Delhi, India

Correspondence to: Dr Daman Saluja, 8/5, Block #41, Singh Sabha Road, Delhi-110007, India; [email protected]

Accepted 22 April 2002

We are grateful to the director, Centre for Biochemical Technology, for extending their facilities for DNA sequencing to us. We thank Ms Leelamma Peter for excellent technical assistance. One of us (UC) is grateful to CSIR for the award of senior research fellowship.

CONTRIBUTORS KR (head, STD laboratory) and MB collected the clinical samples and conducted the drug sensitivity for Neisseria gonorrhoeae; UC carried out PCR and analysis of mutations in the QRDR region of gyrA and parC genes; DS instigated the project, designed the study, and analysed the data; DS and UC wrote the manuscript.

Sexually Transmitted Infections 78(6):p 440-444, December 2002.

Aim:

To analyse mutations in the gyr A and par C 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, gyr A and par C 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 gyr A and the par C genes of all these isolates (n = 63) revealed that all isolates which were not susceptible to ciprofloxacin (n=58) had mutation(s) in gyr A and par C 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 gyr A gene. The third mutation of Val-120 to Leu, lies downstream of the quinolone resistance determining region (QRDR) of the gyr A and has not been described before in gonococcus. In addition, both these isolates had a Phe-100 to Tyr substitution in the par C, 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 gyr A alone or together in gyr A and par C could be responsible for such a high resistance.