The effect of different isolation protocols on detection and molecular characterization of C ampylobacter from poultry

We determined whether different methods to isolate C ampylobacter (including the ISO standard 10272:2006‐1) affected the genotypes detectable from poultry, at three points during slaughter: caecal content, neck skin and meat. Carcasses from 28 independent flocks were thus sampled (subset A). In addition, ten neck skin samples from four flocks, ten caecal samples from ten different flocks and ten unrelated meat samples obtained from local supermarkets were collected (subset B). C ampylobacter was isolated using eight different protocols: with and without enrichment using B olton broth, P reston broth or C ampyfood broth ( CFB ), followed by culture on either modified C harcoal C efoperazone D eoxycholate A gar (m CCDA ) or C ampyfood agar ( CFA ). All obtained isolates were genotyped for fla A ‐ SVR , and over half of the isolates were also typed by MLST . The strain richness, as a measure of number of detected fla‐genotypes, obtained from subset A neck skin and caecal samples was higher than that of meat samples. In half of the cases, within a flock, at least one identical fla‐genotype was obtained at all three slaughter stages, suggestive of autologous contamination of carcasses. Enrichment reduced the observed richness of isolates, while CFA plates increased richness compared to m CCDA plates, irrespective of inclusion of an enrichment step. Because the isolation protocol used influences both the yield and the fla‐genotype richness obtained from poultry, this variable should be taken into account when different studies are being compared. Significance and Impact of Study The tracing of C ampylobacter through the food chain remains important to control campylobacteriosis in humans. Our study points out that the isolation method used affects the genotypes obtained, and this should be considered as a variant when comparing the results of surveillance studies.