THE PREVALENCE OF VIBRIO SPP. IN DRINKING-WATER AND ENVIRONMENTAL-SAMPLES IN VELLORE SOUTH-INDIA

The prevalence of Vibrio cholerae in drinking water, lakes and sewage outfalls during July and August 1996 in Vellore, India was determined. Drinking water samples were collected on single occasions from 12 sit es in different geographic areas of the town where cholera had been re ported. Samples of water, plankton and sediment were collected from fi xed sites at three lakes on three occasions separated by at least 3 da ys during the course of the study. Samples from open sewers were taken from two representative sites in four areas of the town. Bacteria iso lated from samples were identified by standard biochemical tests and i solated strains of V. cholerae tested for their ability to agglutinate O1 and O139 antisera. Water samples from lakes were also tested for t he presence of V. cholerae O1 and O139 by fluorescent antibody stainin g. Non-Ol, non-O139 strains of V, cholerae were detected in 41% of dri nking water samples and 100 % of water, sediment and plankton samples from the test lakes. Eighty-seven per cent of open sewers sampled cont ained viable non-Ol, non-O139 V. cholerae. Fluorescent antibody staini ng gave positive results for V. cholerae O1 and O139 for all water sam ples from the three lake sites. Strains of Aeromonas spp. were isolate d from 58 % of drinking water samples and from 66 % of sediment, 77 % of plankton and 55 % of water samples from lakes. All open sewers samp led contained Aeromonas spp. PCR amplification employing specific prim ers demonstrated that none of the non-agglutinating V. cholerae isolat es contained the ctx operon. The non-Ol, non-O139 V. cholerae isolates showed different patterns of antibiotic resistance to ampicillin, cip rofloxacin, chloramphenicol, tetracycline and trimethoprim.