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 sites in different geographic areas of the town where
cholera had been
reported. Samples of water, plankton and sediment were collected from fixed
sites at three
lakes on three occasions separated by at least 3 days during the course
of the study. Samples
from open sewers were taken from two representative sites in four areas
of the town. Bacteria
isolated from samples were identified by standard biochemical tests
and isolated strains of V.
cholerae tested for their ability to agglutinate O1 and O139
antisera. Water samples from lakes
were also tested for the presence of V. cholerae O1 and
O139 by fluorescent antibody staining.
Non-O1, non-O139 strains of V. cholerae were detected
in 41% of drinking water samples and
100% of water, sediment and plankton samples from the test lakes. Eighty-seven
per cent of
open sewers sampled contained viable non-O1, non-O139 V. cholerae.
Fluorescent antibody
staining gave positive results for V. cholerae O1 and
O139 for all water samples from the three
lake sites. Strains of Aeromonas spp. were isolated from
58% of drinking water samples and
from 66% of sediment, 77% of plankton and 55% of water samples from lakes.
All open
sewers sampled contained Aeromonas spp. PCR amplification employing
specific primers
demonstrated that none of the non-agglutinating V. cholerae
isolates contained the ctx operon.
The non-O1, non-O139 V. cholerae isolates showed different patterns
of antibiotic resistance to
ampicillin, ciprofloxacin, chloramphenicol, tetracycline and trimethoprim.