Prevalence of cytolethal distending toxin (cdt) genes and CDT production in Campylobacter spp. isolated from Danish broilers.

The pathogenesis of campylobacter infection in man is largely unknown, although cytolethal distending toxin (CDT) has been incriminated as a virulence factor. However, little is known about the cdt genes in Campylobacter spp. isolated from broiler chickens. A total of 350 cloacal swabs was collected and tested by conventional culture and PCR. Of the 114 Campylobacter isolates obtained, 101 (88.6%) were identified as C. jejuni and 13 (11.4%) as C. coli by conventional methods. cdt genes were detected by PCR in all the isolates except one C. jejuni isolate. Cytotoxic effects were produced in a Vero cell line, by 100 of the C. jejuni isolates. In contrast, 10 C. coli isolates produced much lower levels of toxin and 3 produced no detectable toxin. These results confirm the common occurrence of campylobacter infection in chickens and indicate that cdt genes are commonly present in both C. jejuni and C. coli isolates from broilers, but that there are distinct differences in CDT production in these two closely related species.