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TP 119 Molecular Analysis of Ciprofloxacin Resistance in Neisseria gonorrhoeae Isolates Collected from STD Patients from Across the Country

Tuesday, June 10, 2014
Exhibit Hall
Seema Sood, MD1, Madhav Agarwal, MSc1, Manju Bala, MD, PhD2, Neeraj Mahajan, MSc1, Rajendra Singh, MSc1, Arti Kapil, MD1, V Sreenivas, PhD3, R.J Ram, MD4, Hemanta K Kar, MD5 and Vinod K Sharma, MD6, 1Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India, 2Apex Regional STD Teaching, Training & Research Centre, VMMC and Safdarjang Hospital, New Delhi, India, 3Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India, 4Department of Dermatology, Lal Bahadur Shastri Hospital, Delhi, India, 5Department of Dermatology, P.G.I.M.E.R. and Dr. Ram Manohar Lohia Hospital, New Delhi, India, 6Department of Dermatology & Venereology, All India Institute of Medical Sciences, New Delhi, India

Background: The public health burden related to N. gonorrhoeae infections is heightened by the high levels of resistance to previously used antimicrobials including fluoroquinolones. However, data on specific genetic events leading to ciprofloxacin resistance in Indian isolates is limited. This study was undertaken to investigate the mutations in gyrA and parC genes in isolates from across the country exhibiting a range of MICs to ciprofloxacin.  

Methods: A total of 82 isolates (Delhi 64; Manipur 7; Srinagar 1; Madurai 5; Mumbai 5-centers of ICMR study) collected from STD patients during November 2010 to October, 2012 were studied. Antimicrobial susceptibility testing was done by disc-diffusion method and E test & results were interpreted as per CDS criteria. DNA sequence analysis of gyrA and parC gene was done as previously described. N. gonorrhoeae WHO F (ciprofloxacin-S) and K, M (ciprofloxacin-R) were used as controls.   

Results: Out of 82 isolates tested, only 2 (2.4%) were susceptible to ciprofloxacin while 7 (8.5%) were less-susceptible & 73 (89%, 95% CI: 80.2% - 94.9%) were resistant (MIC ≥ 1µg/ml). Amongst these, 45 (61.6%, 95% CI: 49.5% – 72.8%) demonstrated high-level resistance, i.e., HLR (MIC ≥ 4 µg/ml).  A S91F substitution in gyrA gene was demonstrated in all ciprofloxacin non-susceptible isolates. All resistant isolates demonstrated double mutations in gyrA gene. This was coupled with single mutation in parC gene in 20/28 (71.4%, 95% CI: 51.3% - 86.8%) with MIC 1-3 µg/ml and 43/45 (95.6%, 95% CI: 84.9% - 99.5%) of isolates with MIC ≥ 4 µg/ml. Double mutations in parC gene were observed in 2 isolates in MIC range of 1-3 µg/ml and 2 in MIC≥ 4 µg/ml. In addition, S87R mutation in parC gene was restricted only to HLR strains. One isolate (MIC 32 µg/ml) had a previously undescribed G85D substitution in the parC gene.

Conclusions: It was observed that the number of mutations in parC gene does not determine the level of ciprofloxacin resistance. Perhaps the efflux pump plays a significant role and warrants further investigation.