Phenotypic and genotypic characterization of antimicrobial resistance in clinical isolates of Vibrio cholerae over a decade (2002-2016)

Purpose: Emergence and spread of resistance among Vibrio cholerae have become a global public health problem. In India, no consolidated data is available on antimicrobial susceptibility patterns and antibiotic resistance genes. Methods: A total of 110 representative isolates obtained over a period of 14 years were included. Antimicrobial susceptibility was tested by disc diffusion and micro broth dilution. Presence of 13 antimicrobial resistance genes was ascertained by using PCR. Results: Antimicrobial resistance fluctuated for most of the antibiotics. Resistance to cotrimoxazole in our study was 92.72% and the SXT element was present in all isolates. Resistance to nalidixic acid, tetracycline, and cefotaxime was found to be 98.18%, 7.27%, and 10.9% respectively. Resistance to ampicillin saw a fluctuating trend with a recent fall. Resistance to ciprofloxacin and azithromycin was 12.72% and 29% by MIC. bla(TEM) was the most common ESBL gene (94.5%). Other were bla(CMY) (26.36%) and bla(NDM) (2.7%). We report bla(CTX-M-15) and bla(OXA-48) and ermB for the first time in the world. Newer antimicrobials like prulifloxacin and rifaximin were tested for the first time from India. Conclusions: Our study has shown very high levels of resistance to older antibiotics and the emergence of resistance to some of the newer classes of antibiotics. There is an urgent need for increased surveillance studies, rational use of the antimicrobials and preventive measures to control the disease.