PCR identification of Campylobacter coli and Campylobacter jejuni by partial sequencing of virulence genes

The objective of this study was to utilize a multiplex PCR assay for concurrent detection of Campylobacter spp. and C. coli or C. jejuni, using probes derived from genes cadF and ceuE and an undefined virulence gene. A total of 97 Campylobacter strains, isolated from turkey litter (n=74), chicken livers (n=15) and clinical (n=8) samples, were speciated using the PCR-based assay. PCR amplification of the isolates identified a 400-bp cadF gene, conserved in Campylobacter species, an 894-bp ceuE gene, specific for C. coli, and a 160-bp oxidoreductase gene, specific for C. jejuni. The approximately 35 kDa cadF adhesion proteins allow Campylobacter to bind to the intestinal epithelial cells and the 37 kDa ceuE lipoproteins are involved in siderophore transport. Sequencing of the 160-bp undefined gene yielded a 67% protein identical match with a gene encoding an oxidoreductase subunit in C. jejuni. The specificity of the assay was validated on 36 non-Campylobacter strains (11 Gram-positive and 25 Gram-negative bacteria). The PCR assay identified 59% of turkey and 47% of chicken isolates as C. jejuni, and 41% of turkey and 53% of chicken isolates as C. coli. All human isolates were identified as C. jejuni. The specificity of this assay to detect C. coli or C. jejuni was 97%.