Evaluation of the different rinse volumes for performing the direct technique for Campylobacter spp. enumeration in chilled broiler carcasses

Abstract

The direct method for detecting and enumerating Campylobacter spp. in chicken meat is easy to perform, but the volumes of 100μL and 400μL, as recommended in some methodologies, are often unable to achieve the colonies counts due to the occurrence of confluent growth or microbial contaminants. This study aimed at evaluating the different volumes for rinsing chicken meats in order to minimize the interference of microbial contaminants, without compromising the sensitivity of direct methodology. Rinse volumes of 5, 10, 50, 100 and 400μL were tested using the modified charcoal cefoperazone deoxycholate agar (mCCDA) and modified Bolton agar. The presence of Campylobacter was confirmed by phenotypic methods and PCR assay. However, the strategy of using less than 100 μL of rinse volumes did not improve the isolation and enumeration of Campylobacter colonies, because it reduces the sensitivity of the assay. Thus, a possible solution to minimize the interference of microbial contaminants would be in developing new selective media or incorporate them into other existing antimicrobial drugs.