Oligonucleotide primers
All oligonucleotide primers used in this study were synthesized
by Invitrogen-Life Technologies (Shanghai
Yingjun Biotechnology Co., Ltd.). The target genes
selected for their characteristic were the invA (invasion
protein A) gene in Salmonella [18], the hlyA (transcriptional
activator of the virulence factor) gene in L. monocytogenes
[19], the rfbE (attaching and effacing A) gene in
E. coli O157:H7 [20], the nuc (thermonuclease) gene in S.
aureus [21] and the ail (chromosomal location) gene in Y.
enterocolitica [22], all of which have been reported in the
recent publications as the most specific and reliable genetic
targets for the five pathogens.