A group of gram negative, lactose fermenting, bacteria characterised operationally by ability to grow in specified culture media under specified conditions rather by any taxonomic considerations. The number of coliform organisms in a sample is typically estimated by the Most Probable Number (MPN) method. Coliforms include the group of faecal coliforms and high numbers of coliforms in a sample is an indication that faecal coliforms, and perhaps food poisoning organisms of enteric origin might be present. It is more satisfactory for monitoring the hygienic condition of fishery products to test for faecal coliforms, but coliform count is simpler to conduct, and quicker to produce a result.