[Occurrence and identification of enterotoxin-producing E. coli strains in milk and dairy products]

Enteric diseases caused by enterotoxigenic E. coli strains (ETEC) become more and more important all over the world. Frequently food is implicated as a vector. --From this the necessity arises to identify ETEC strains and/or their heatlabile (LT) and heat-stable enterotoxins (ST). The examinations carried out for the presented paper showed the following results: Detection of LT by coagglutination is a simple and rapid test and may be helpful for screening. Most suitable, however, is the application of ELISA which enables the detection of 1 ng/ml LT with a good reproducibility. For identification of ST the suckling mouse assay (SMA) yields reliable results. ELISA and SMA have proved to be useful in practice for examination of food samples. By means of these methods 157 E. coli strains predominantly isolated from milk and milk products were examined. Hereby, five ETEC strains could be identified (3.2%). For the purpose of food examination a procedure was developed which ensures a reliable and efficient identification of E. coli enterotoxin. The essential steps are enrichment in E.E.-broth, subcultivation in CAYE-2-broth, identification of LT by ELISA resp. coagglutination and the detection of ST with aid of the SMA. So, isolation of single colonies can be omitted, which is an essential advantage.