Evaluation of a PCR detection method for Escherichia coli O157:H7/H- bovine faecal samples

Aims: Combinations of PCR primer sets were evaluated to establish a multiplex PCR method to specifically detect Escherichia coli O157:H7 genes in bovine faecal samples. Methods and Results: A multiplex PCR method combining three primer sets for the E. coli O157:H7 genes rfbE, uidA and E. coli H7 fliC was developed and tested for sensitivity and specificity with pure cultures of 27 E. coli serotype O157 strains, 88 non-O157 E. coli strains, predominantly bovine in origin and five bacterial strains other than E. coli. The PCR method was very specific in the detection of E. coli O157:H7 and O157:H- strains, and the detection limit in seeded bovine faecal samples was < 10 CFU g(-1) faeces, following an 18-h enrichment at 37 degrees C, and could be performed using crude DNA extracts as template. Conclusions: A new multiplex PCR method was developed to detect E. coli O157:H7 and O157:H-, and was shown to be highly specific and sensitive for these strains both in pure culture and in crude DNA extracts prepared from inoculated bovine faecal samples. Significance and impact of Study: This new multiplex PCR method is suitable for the rapid detection of E. coli O157:H7 and O157:H- genes in ruminant faecal samples.