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Indian Journal of Medical Microbiology, Vol. 27, No. 2, April-June, 2009, pp. 166-167 Correspondence Circulating phage type of Vibrio cholerae in Mysore Srirangaraj S, Venkatesha D Department of Microbiology, Mahathma Gandhi Medical College and Research Institute, Pondicherry - 607 402 Date of Submission: 15-Dec-2008 Code Number: mb09050 PMID: 19384046 DOI: 10.4103/0255-0857.49436 Dear Editor, Cholera is an important public health problem in India. Bacteriophage typing is a convenient and highly discriminatory method of identifying epidemic strains of Vibrio cholerae . Constant monitoring of the prevalent phage types in an area is important as introduction of a new phage type may herald the onset of an outbreak. [1] A total of 14 strains of V. cholerae were isolated from 56 stool samples received from patients with acute diarrhoea who were admitted to the K.R. Hospital, Mysore Medical College and Research Institute, Mysore, between 2 May 2007 and 30 June 2007. The isolation was carried out using standard laboratory techniques at the Department of Microbiology, Mysore Medical College and Research Institute, Mysore. Alkaline peptone water was used for the preliminary enrichment of vibrios from the faeces. All the samples were plated onto MacConkey agar, blood agar and TCBS medium. [2] The suspected colonies were subjected to Gram stain, oxidase, motility and string tests. The Gram negative rods that were oxidase positive, actively motile and string test positive were subjected to further biochemical tests. [3] These were indole, triple sugar iron agar, cholera-red reaction, citrate utilization, ornithine decarboxylase, lysine decarboxylase, arginine dihydrolase and sugar fermentation tests using sucrose, mannitol, arabinose and mannose. [2] Biotyping was performed by the Voges-Proskauer test, chick red cell agglutination test, sheep RBC haemolysis test and Polymyxin-B (50 unit disc) sensitivity test. [3] Serotyping was carried out by slide agglutination using Ogawa and Inaba antisera. [2] All the 14 isolates belonged to the V. cholerae ElTor biotype and Ogawa serotype. These isolates were confirmed at the National Institute of Cholera and Enteric Diseases, Kolkata, where phage typing was performed. All the isolates identified belonged to the Basu and Mukherjee phage type T 2 . This finding is in contrast with several studies from Mumbai, [1] Bikaner [4] and Ludhiana [5] , where all the strains belonged to phage type T 4 . At present, the prevalent biotypes in India are T 2 and T 4 . [6] But, in the present study, the new phage typing scheme against V. cholerae O1 ElTor strains showed the following four phage types: T27, T21, T25 and T23 [Table - 1]. The majority of the isolates belonged to type 27 (78.58%, i.e. 11 isolates). The pattern of phage typing nearly coincides with that of a study reported by Gupta et al. (79.69%, 51 isolates) in the year 1999. [4] Thus, T 27 is the predominant phage type reported from studies in Bikaner [4] and Mumbai, [1] as in the present study . In the present study, one isolate each (7.14%) belonged to type 23, type 25 and type 21.Of these, one was an imported one (T-23 was isolated from a 6-year-old girl from Nanjangud, situated outside Mysore). The new scheme was thus more discriminatory and could identify four circulating phage types when compared with a single phage type identified by the Basu and Mukherjee scheme. Acknowledgements The authors are grateful to the National Institute of Cholera and Enteric Diseases, Calcutta, for confirming and phage typing the V. cholerae isolates. The authors are also grateful to Dr. Ramesh Rao and Dr. Maruthi P for their help and support. References
Copyright 2009 - Indian Journal of Medical Microbiology The following images related to this document are available:Photo images[mb09050t1.jpg] |
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