Abstract:

Four pairs of specific primers were designed according to the sequences of the LT gene from enterotoxigenic E.coli (ETEC), the bfpA gene from enteropathogenic E.coli (EPEC), the O antigen gene from enterohemorrhagic E.coli (EHEC) and the invasive plasmid gene from enteroinvasive E.coli (EIEC) for the development of a multiplex polymerase chain reaction/denaturing high performance liquid chromatography (PCR/DHPLC) method for the simultaneous detection of the four common diarrheogenic E.coli strains. The PCR/DHPLC method had high sensitivity and its detection limit was 6×101 copies/μL for EHEC, 1.3×102 copies/μL for ETEC, 9×101 copies/μL for EPEC and 7×101 copies/μL for EIEC. The specificity evaluation showed that 6 of 41 stains from 22 species were determined to be positive. This method proves to be applicable and suitable for the detection of infection with one or more of the four E.coli strains.

Key words: diarrheogenic E.coli, PCR, DHPLC, detection