The implications of switching from total coliform to Enterobacteriaceae as an indicator organism in a food manufacturing facility: a literature review

Coliform is the traditional indicator organism of choice for testing of the environment and finished food products in the United States, as current reflected in some federal rules, such as the Pasteurized Milk Ordinances. A positive test result can indicate the presence of potential pathogenic activity, which at its worst can cause adverse reactions to human health but can also have no ill effects. Further research, however, has proven that the scope of this test is limited in what it can detect. An alternative indicator test, Enterobacteriaceae, can pick up not only the bacteria falling under the standard definition of coliform, but also other gram-negative bacteria and potential pathogens, making this test more robust and thorough. A third option – for gram-negative bacteria, generally – would offer the most comprehensive indicator organism testing program, when combined with Enterobacteriaceae. This paper reviews relevant research studies regarding these first two indicator organism tests, concluding that Enterobacteriaceae is the superior test for the food manufacturing environment, with a focus on finished ready-to-eat food products. Testing for these pathogenic indicators has evolved from agar testing, which could take days, to 3M’s Petrifilm, which can take several hours to incubate and reveal possible contamination. The Petrifilm test can also help food safety practitioners differentiate between contaminants from the environment versus bacteria that are naturally present in certain foods, such as cheese. In fact, some members of the coliform family can be beneficial to cheese curing and ripening. In switching from coliform to Enterobacteriaceae, any company would be catching up to the European Union, which has used this test since 2005 as its pathogenic indicator test for ready-to-eat dairy products. Although the literature reviewed in this paper does point to Enterobacteriaceae as the superior test, some may be required to continue coliform testing in finished products to meet customer requirements and certain federal rules.