Brief Original Article

Introduction: Considering the changing geographical and temporal occurrence of Vibrio cholerae, there is a continuing need to monitor the strain characteristics and antibiotic resistance patterns of this pathogen. The present study was conducted to document the changing biology of V. cholerae isolates in and around Delhi, India, and the development of antibiotic resistance. Methodology: A total of 1,424 stool samples or rectal swabs from patients with acute secretory diarrhoea admitted to Guru Teg Bahadur Hospital, Delhi, between January 2007 and December 2009 were processed using standard bacteriological methods. Strains identified as V. cholerae were further subjected to serogrouping, phage typing and antimicrobial susceptibility testing. Minimum inhibitory concentration (MIC) of gentamicin and tetracycline was determined. Results: V. cholerae was isolated in 242/1,424 (17.0%) specimens. Of these, the majority were V. cholerae O1 serotype (98.3%) and serovar Ogawa. The drugs to which V. cholerae O1 isolates showed high levels of resistance were nalidixic acid, furazolidone, and cotrimoxazole throughout the study period, whereas strains were usually susceptible to chloramphenicol and cefotaxime. In 2007, there was a sudden increase of resistance to gentamicin and tetracycline, followed by a slow reversal to previous levels in subsequent years. The phage typing pattern (Basu and Mukherjee scheme) showed a dominance of phage type 2 throughout the study period. Conclusion: The importance of reporting all cases of V. cholerae, should be greatly emphasized, with the ultimate goal of understanding the constantly changing resistance patterns of this pathogen.