Potentially pathogenic bacteria isolated from different tropical waters in Sri Lanka

This study investigated the bacteriological contamination of different water sources in Sri Lanka. Source waters (n = 74) including bottled water, well water and surface water were assessed for enumerating total coliforms and faecal coliforms using the membrane filtration method. The results showed that 18.5 and 14.8% of bottled water samples were contaminated with total coliforms and faecal coliforms, respectively. All the well water and surface water samples exceeded the WHO permitted levels for total coliforms and faecal coliforms. Bacteriological identification using biochemical tests and api 20E identification tests revealed the presence of potentially pathogenic bacteria in all water sources tested. Bottled water mainly contained three Enterobacter species, while well water samples showed the broadest spectrum of bacteria including eleven coliform species belonging to the genera Klebsiella, Escherichia, Enterobacter, Citrobacter, Kluyvera, Pantoea, Rautella, and 10 non-coliform species in the genera Pseudomonas, Aeromonas, Salmonella and Acinetobacter. Surface waters contained seven coliform species belonging to the genera Klebsiella, Escherichia, Citrobacter, Rautella and Serratia, and eight non-coliform species in the genera Pseudomonas, Aeromonas and Acinetobacter. Detection of higher bacteriological counts and identification of potentially pathogenic bacteria in different source waters suggest a potential health risk of the water sources used in Sri Lanka.