Colitag, by CPI International, is a ready-to-use ONPG/MUG based test, which can be added directly to a liquid or semi-liquid sample. If coliforms are present, ONPG will produce a distinct yellow color. If E. coli is present, the sample will fluoresce a bright blue color under long-wave (366 nm) UV light. Incubation of the test is performed at 35° C for 22-26 hours.
Colitag is capable of resuscitating and detecting even single cells of severely injured E. coli and coliforms, the company said. Preliminary testing has shown promising results for monitoring shellfish meats and shellfish-growing waters, as well as for waters growing alfalfa sprouts. Coliforms are a group of closely related bacteria that are (with a few exceptions) generally not harmful to humans. However, they include species present in the intestines of warm-blooded animals, and thus are often associated with disease outbreaks. For this reason, they are considered “indicator organisms” and their presence is used as a sign of the potential risk of illness from disease causing organisms associated with sewage or animal wastes.