Polymerase chain reaction detection of naturally occurring Campylobacter in commercial broiler chicken embryos

Campylobacter, a foodborne pathogen closely associated with poultry, is recognized as a leading bacterial etiologic agent of human gastroenteritis in the United States. In this investigation, 2 trials were performed where tissues from 7-, 14/15-, and 19-d-old commercial broiler chicken embryos were tested for the presence of Campylobacter using both culturing methodology and PCR. Conventional culturing methods failed to detect Campylobacter from any samples tested during this investigation. Using a set of primers specific for the Campylobacter flagellinA short variable region (flaA SVR), Campylobacter DNA was amplified in 100, 80, and 100% of gastrointestinal tracts from 7-, 15-, and 19-d-old embryos, respectively, in the first trial. Similarly, Campylobacter DNA was detected in 100, 70, and 60% of gastrointestinal tracts of 7-, 14-, and 18-d-old embryos, respectively, in the second trial. In both trials, yolk sac, albumin, and liver/gallbladder samples from 19-d-old embryos all failed to produce amplicons indicative of Campylobacter DNA. Subsequent DNA sequence analyses of the flaA SVR PCR products were consistent with the amplicon arising from Campylobacter. Although a determination of whether the Campylobacter was living or dead within the embryos could not be made, these results demonstrate that Campylobacter-specific DNA is present within the gastrointestinal tract of broiler chicken embryos; however, the means by which it is present and the relative contribution to subsequent Campylobacter contamination of poultry flocks requires further investigation.