Retrospective analysis to study trend of biotype, serotype and phage type of Vibrio cholerae isolates in South Gujarat over last 17 years

Introduction: Cholera is a major infectious disease with epidemic potential, especially among communities living in congested urban slums and vast rural areas without proper sanitary facilities. Epidemiology of cholera showed remarkable changes soon after the identifi cation of El Tor biotype of Vibrio cholerae in India in 1964. The classical biotype reported in earlier years was believed to have become extinct in the recent past. Presently, V. cholerae O1 belonging to the El Tor biotype is most common in India. Materials and Methods: A retrospective study was carried out in Department of Microbiology to study the epidemiological pattern of V. cholerae in South Gujarat. V. cholerae isolates were confi rmed by various biochemical tests. Agglutination was done with antisera. All the isolates were sent to the National Institute of Cholera and Enteric Diseases, Kolkata for phage typing. Antibiotic susceptibility was carried out by Kirby Bauer disc diffusion technique. Result: 98% of the isolates were of El Tor biotype and 2% of non O1 non O139. 98.8% of the isolates were of Ogawa serotype, only 1.2% of Inaba. According to Basu and Mukerjee classifi cation, T-2 phage was found in 76% isolates. T-4 phage was seen during 1995-1996 and 2002-2004 only. According to the new scheme classifi cation, T-27 phage type was found in 74% isolates followed by T-25 (4%), T-19 (3.7%) and T-25 (3%). Conclusion: T-2 is predominant serotype found in South Gujarat region and was constant since 2005 onwards. El Tor biotype was found commonly and no isolation of classical biotype was seen. Data analysis will help for future studies.