Development of procedures for rapid detection of E. coli O157:H7 from source and finished water samples

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7, the causative agent for haemolytic uraemic syndrome, has become a significant health concern, due to an increasing number of cases. The focus of this project was rapid (<8 h) detection of E. coli O157:H7 from source and finished waters samples, either directly or indirectly, by dovetailing the procedures with existing total coliform procedures. Evaluation of four immunological lateral diffusion assays determined a detection range between 1 x 10(4) and 1 x 10(6) CFU, with the Reveal E. coli O157:H7 Test System (Neogen) being the most sensitive for detecting E. coli O157:H7. Evaluation of the BAX System for molecular detection determined that as few as 10 CFU could be reproducibly detected. Coupling either of these detection procedures with organism propagation using Tryptic Soy Broth (TSB) enabled sufficient quantities of E. coli O157:H7, such that the Reveal and BAX detection methods could be used with the 8 h time frame. Examination of matrix effects on the overall procedure indicated little impact on method performance.