Hatha, A A M; Abhirosh, C; Sherin, V; Thomas, A P; Mazumder, A(Elsevier, March 23, 2011)
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Abstract:
To assess the prevalence of faecal coliform bacteria and multiple drug resistance
among Escherichia coli and Salmonella serotypes from Vembanadu Lake.
Study design: Systematic microbiological testing.
Methods: Monthly collection of water samples were made from ten stations on the southern
and northern parts of a salt water regulator constructed in Vembanadu Lake in order to
prevent incursion of seawater during certain periods of the year. Density of faecal colifrom
bacteria was estimated. E. coli and Salmonella were isolated and their different serotypes
were identified. Antibiotic resistance analysis of E. coli and Salmonella serotypes was done
and the MAR index of individual isolates was calculated.
Results: Density of faecal coliform bacteria ranged from mean MPN value 2900 -7100/100ml.
Results showed multiple drug resistance pattern among the bacterial isolates. E. coli
showed more than 50% resistance to amickacin, oxytetracycline, streptomycin, tetracycline
and kanamycin while Salmonella showed high resistance to oxytetracycline, streptomycin,
tetracycline and ampicillin. The MAR indexing of the isolates showed that they
have originated from high risk source such as humans, poultry and dairy cows.
Conclusions: The high density of faecal coliform bacteria and prevalence of multi drug
resistant E. coli and Salmonella serotypes in the lake may pose severe public health risk
through related water borne and food borne outbreaks
Hatha, A A M; Abhirosh, Chandran; Suson, P S; Thomas, A P; Asit, Mazumder(I W A Publishing, February 11, 2013)
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Abstract:
The objective of the study was to evaluate the survival response of multi-drug resistant
enteropathogenic Escherichia coli and Salmonella paratyphi to the salinity fluctuations induced by a
saltwater barrier constructed in Vembanadu lake, which separates the lake into a freshwater
dominated southern and brackish water dominated northern part. Therefore, microcosms containing
freshwater, brackish water and microcosms with different saline concentrations (5, 10, 15, 20, 25
ppt) inoculated with E. coli/S. paratyphi were monitored up to 34 days at 20 and 30 WC. E. coli and
S. paratyphi exhibited significantly higher (p <0.05) survival at 20 WC compared to 30 WC in all
microcosms. Despite fresh/brackish water, E. coli and S. paratyphi showed prolonged survival up to
34 days at both temperatures. They also demonstrated better survival potential at all tested saline
concentrations except 25 ppt where a significantly higher (p<0.0001) decay was observed.
Therefore, enhanced survival exhibited by the multi-drug resistant enteropathogenic E. coli and S.
paratyphi over a wide range of salinity levels suggest that they are able to remain viable for a very
long time at higher densities in all seasons of the year in Vembanadu lake irrespective of saline
concentrations, and may pose potential public health risks during recreational activities