Abstract

Oligonucleotide array hybridisation and multiplex polymerase chain reaction (m-PCR) can be used to screen and detect multiple foodborne pathogens. In our study, m-PCR and oligonucleotide array assays for the specific detection of the dominant foodborne bacterial pathogens, including Escherichia coli, Listeria monocytogenes, Salmonella spp., andShigella spp., in chicken meat were developed. The combination of m-PCR and an oligonucleotide array targeting the 16S rRNA, uspA, prfA, fimY, and ipaH genes displayed a high discriminatory power among the aforementioned genera and species with low or no incidence of false negative results. Our combined methods could detect all 4 target bacteria at amounts as low as 1 ng of each from mixed genomic DNA extracted from pure cultures, which is equivalent to 10⁴-10⁶ CFU/ml. After enrichment steps for the target bacteria, E. coli, L. monocytogenes, and Salmonella sp. could be detected simultaneously from fresh chicken samples. Combining the two methods could enhance accuracy and sensitivity for foodborne pathogen detection and identification. The problems of cross-reactivities from non-target bacteria isolated from an enrichment culture and the difficulties in result interpretation by m-PCR could be solved using our oligonucleotide array hybridisation method.

Key words: Oligonucleotide array, multiplex PCR, foodborne pathogens, target bacteria.

Abbreviation

m-PCR, Multiplex polymerase chain reaction; DIG, digoxigenin; TSA,trypticase soy agar; TSC, tryptose sulphite cycloserine agar; EMB, Eosin-methylene blue agar; XLD, xylose lysine deoxycholate; agar; BS, bismuth sulphite; agar; BPW, buffered peptone water.