Pseudomonas aeruginosa, a food- and water-borne opportunistic pathogen, constitutes a health risk mostly to immunocompromised patients, and also affects the taste, odour and turbidity of potable water. In order to detect P. aeruginosa in bottled water in Sri Lanka, 36 bottled water brands were collected randomly from retail and supermarkets island wide. P. aeruginosa was detected by the membrane filtration technique, using cetrimide agar supplemented with nalidixic acid. The isolates were subjected to confirmatory tests, viz: ISO 16266:2006 methods and growth at 4 and 42°C, and API 20NE followed by DNA sequencing. Presumptive isolates of P. aeruginosa were observed on cetrimide agar in 50% of brands. Among these isolates, ISO procedures confirmed 58% as P. aeruginosa. Thirty-nine randomly selected isolates were identified as P. aeruginosa by the API 20NE, three of which were further confirmed by DNA sequencing. The presence of P. aeruginosa in bottled water raises health concerns since P. aeruginosa is an indicator of inferior water quality. Therefore, strict regulations and regular monitoring of bottling plants are recommended in order to supply safe and acceptable bottled drinking water to the Sri Lankan market.

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