Detection and quantification of Campylobacter spp. in Brazilian poultry processing plants

Campylobacteriosis is considered the most common bacteria-caused human gastroenteritis in the world. Poultry is a major reservoir of Campylobacter. Human infection may occur by consumption of raw and undercooked poultry or by contamination of other foods by these items. The aim of this study was to assess the prevalence of Campylobacter spp. in poultry processing plants with conventional culture method and real-time PCR.

A total of 108 poultry processing plant samples were collected to test with conventional microbiology and qPCR. Sampling included cloacal swabs, swabs of transport crates (before and after the cleaning and disinfection process) and carcasses (after the chiller, cooled at 4°C and frozen at -12°C).

Positivity in cloacal swabs indicated that poultry arrived contaminated at the slaughterhouse. Contamination in transport cages was substantially increased after the cleaning process, indicating that the process was ineffective. The detection of Campylobacter on carcasses was higher than that on cloacal swabs, which could indicate cross-contamination during the slaughtering process. Conventional microbiology and molecular methods revealed a prevalence of 69.4% and 43.5%, respectively. Lower detection by qPCR can be attributed to the high specificity of the kit and to biological components that could inhibit PCR reactions.

Our results indicate that poultry arrive contaminated at the slaughterhouse and that contamination can increase during the slaughtering process due to cross-contamination. The isolation of Campylobacter in cooled and frozen carcasses corroborates the bacterial survival even at temperatures considered limiting to bacterial growth which are routinely used for food preservation.