Detection of Campylobacter spp. in ceca and crops with and without enrichment

The purpose of this experiment was to determine how sampling method (direct plating or enrichment) affected the rate of Campylobacter spp. isolation from crop and cecal samples. In four separate trials, 32 New York-dressed broiler carcasses were obtained from commercial plants (n = 128). Crops and ceca were removed aseptically, direct plated, and enriched. Samples were direct-plated on Campy-Cefex plates that were incubated at 42 C for 36 to 48 h under a microaerobic atmosphere (5% O2, 10% CO2, 85% N2). After direct plating, samples were enriched in Bolton broth at 37 C for 4 h and 42 C for 20 h under a microaerobic atmosphere before plating onto Campy-Cefex plates. Campylobacter spp. was detected in 95.3% of direct-plated crop samples and 99.2% of enriched crop samples. Campylobacter spp. was detected in 100% of direct-plated cecal samples and 63.3% of enriched cecal samples. All 128 crop and cecal samples were positive for the organism by one or both methods. Mean counts of Campylobacter spp. were 3.6 log10 cfu/g of crop sample and 6.8 log10 cfu/g of cecal sample. For these two sample types, both of which tend to be contaminated with many viable cells, direct plating is sufficient for isolation of Campylobacter. Direct plating also provides an estimate of contamination level. Enrichment of cecal samples resulted in a decreased rate of detection and did not allow estimation of numbers of Campylobacter. The large numbers of non-Campylobacter species that inhabit the intestinal tract may out-compete Campylobacter during enrichment, confounding detection.