Significance of sample weight and enrichment ratio on the isolation of naturally occurring Campylobacter spp. in commercial retail broiler meat.

The goal of these experiments was to evaluate the efficacy of different meat to broth ratios for the isolation of Campylobacter spp. from retail broiler chicken meat. The evaluation included 25 g of meat enriched in 100 ml of Bolton broth (1:4 ratio, subsample A), 50 g in 200 ml (1:4, subsample B), 100 g in 300 ml (1:3, subsample C), and 150 g in 300 ml (1:2, subsample D). For 29 samples, another subsample (E) was evaluated at a 1:9 ratio. The results from 110 samples revealed no differences (P > 0.05) among subsamples (A through D) for the detection of Campylobacter-positive samples. By adding the results from subsamples A and B, the number of Campylobacter-positive samples was higher (P < 0.05) than that found based on results of subsamples A or B alone. However, the addition of the results from subsamples C and D increased the number of positive samples detected by only three. Subsamples C and D were the most contaminated, and contamination for subsamples A and B depended more on the original contamination of the meat than on the enrichment ratio. The mixing of the meat resulted in detection of more Campylobacter-positive samples than were found when the samples were not mixed before the subsamples were collected. No differences were found in the number of positive samples detected among subsamples A, B, C, or D based on product type. These results suggest that the linear extrapolation of positive results may not be appropriate for predicting the presence of Campylobacter spp. and that a 1:4 enrichment ratio with 25 g of meat is the most practical approach for the isolation of Campylobacter spp. from retail broiler meat.