Bottlers are familiar with Colilert in their day-to-day control of bottled water quality. Colilert from Idexx determines the presence or absence of coliforms in water. Coliforms are not allowed in bottled water and testing is done for every batch of bottled water produced. Coliform bacteria can be found widely in the environment, in soil, water and on vegetation, but are also abundant in the faeces of warm-blooded animals. While coliforms themselves are not normally causes of serious illness, they are easy to culture and their presence is used to indicate that other pathogenic organisms of faecal origin may be present. The test itself is simple and uses a powder which is added to the water sample. After incubation for 24 hours at 37 degrees C, a colour change from clear to yellow indicates the presence of coliforms.
A new kit for determining the presence or absence of Pseudomonas aeruginosa is now available called Pseudalert. The procedure is similar to that indicated above except that the initial colour of the sample is yellow and, after incubation, the presence of Ps. aeruginosa is inicated by the presence of flourescence under UV light. Ps aeruginosa is a pathogen which can cause infections in open wounds. In a water environment, it is often associated with biofilm, a protective slime which serves to protect microorganisms. Ps. aeruginosa is not allowed in bottled water, although it should have little effect on healthy individuals. However, people with a poor immune system, mouth ulcers or throat lesions could be affected. At high levels, the microorganism can cause off-tastes and odours. Currently bottlers are testing for the presence of Ps. aeruginosa in their regular quality checks.
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