Evaluation of the Colilert® test for detection of verotoxin-producing Escherichia coli in water: a tool for on-farm food safety

The sensitivity of the Colilert test for detection of different isolates of E. coli O157:H7 and other verotoxin-producing E. coli (VTEC) serotypes from water was evaluated. E. coli isolates evaluated were of human, bovine, porcine or food origin. The sensitivity of the Colilert test was 92% overall for the verotoxin-producing serotypes of E. coli. However, none of the E. coli O157:H7 isolates were identified as E. coli. No false-positive results for E. coli were detected. It is concluded that the Colilert test could be used to screen water supplies for E. coli on the farm, however, an important pathogenic E. coli serotype is not detected by the Colilert test.