Exploring quinolone resistance-determining region in Neisseria gonorrhoeae isolates from across India
Seema Sood1, Madhav Agarwal1, Manju Bala2, Neeraj Mahajan1, Rajendra Singh1, Arti Kapil1, Vishnubhatla Sreenivas3, RJ Ram4, Hemanta Kumar Kar5, Vinod Kumar Sharma6, for ICMR Collaborative Study*7
1 Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India
2 Apex Regional STD, Teaching, Training & Research Centre, Vardhman Mahavir Medical College & Safdarjung Hospital, New Delhi, India
3 Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India
4 Department of Dermatology, Lal Bahadur Shastri Hospital, Delhi, India
5 Department of Dermatology, STDs & Leprosy, Postgraduate Institute of Medical Education and Research & Dr Ram Manohar Lohia Hospital, New Delhi, India
6 Department of Dermatology & Venereology, All India Institute of Medical Sciences, New Delhi, India
Department of Microbiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110 029
Source of Support: None, Conflict of Interest: None
Background & objectives: Antimicrobial resistance in Neisseria gonorrhoeae, the causative agent of gonorrhoea, is a subject of worldwide attention. The present study was undertaken to examine the rates of ciprofloxacin resistance, to correlate mutations in gyrA and parC genes with the level of resistance and to look for a variation in mutation pattern, if any, in isolates from across the country.
Methods: A total of 113 isolates of N. gonorrhoeae collected from sexually transmitted infection patients in six centres during November 2010 to October 2013 were investigated. Minimum inhibitory concentration (MIC) determination was done by E-test and results interpreted as per Calibrated Dichotomous Sensitivity criteria. DNA sequence analysis of gyrA and parC genes was done.
Results: Of the 113 isolates, only three (2.6%) were susceptible whereas eight (7.07%) were less susceptible, 32 [28.3%, 95% confidence interval (CI): 20.4-37.6%] resistant (MIC 1-3 μg/ml) and 70 (61.9%, 95% CI: 52.2-70.7%) exhibited high-level resistance (HLR) (MIC ≥4 μg/ml) to ciprofloxacin. A S91F substitution in gyrA gene was demonstrated in all ciprofloxacin non-susceptible isolates. All resistant and HLR isolates had a double mutation in gyrA gene. However, only 5.7 per cent of HLR isolates showed double mutations in parC gene. One isolate (MIC 32 μg/ml) had a previously undescribed G85D substitution in the parC gene.
Interpretation & conclusions: A S91F substitution in gyrA gene was seen in all non-susceptible isolates of N. gonorrhoeae. It may be used as a marker for ciprofloxacin resistance for molecular surveillance approaches to complement the culture-based methods.