Contamination of carcasses, offals, and the environment with yadA-positiveYersinia enterocolitica in a pig slaughterhouse

This study was carried out in order to evaluate the contamination of the pi g-slaughtering line with pathogenic Yersinia enterocolitica carrying the ya dA gene. A total of 292 samples were collected from the slaughterhouse; 131 swab samples from pig carcasses, ears, livers, kidneys, and hearts; 89 swa b samples from the environment; and 72 sedimentation samples from the air. All surface samples were studied with both the polymerase chain reaction (P CR) and culture methods. The contamination rate of edible pig offals was hi gh with both methods. Using PCR, the detection rates of yadA-positive Y. en terocolitica for livers, kidneys, and hearts were 38, 86, and 63%, respecti vely, and using the culture method, the detection rates were 31, 69, and 50 %, respectively. Pathogenic Y. enterocolitica was also detected from differ ent environmental sites in the slaughterhouse. Using PCR, 13% of the surfac e samples from the environment were contaminated with yadA-positive Y. ente rocolitica. PCR-positive samples were found on the brisket saw, the hook fr om which the pluck set (heart, lungs, esophagus, trachea, diaphragm, liver, kidneys, and tongue with tonsils) hang, the knife used for evisceration, t he floors in the eviscerating area and the weighing area, the meat-cutting table, the aprons used by trimming workers, the computer used in the meat-i nspection area, and the coffeemaker used by slaughterhouse workers. The res pective detection rate (6%) was considerably lower when we used the culture method. Pathogenic Y. enterocolitica was isolated from the air in the blee ding area. Bioserotype 4/O:3 was the only pathogenic bioserotype isolated i n this study. A total of 113 isolates of type 4/O:3 were characterized with pulsed-field gel electrophoresis using NotI and XbaI digests. By combining these profiles, nine different pulsotypes were obtained, the most common o f which (la) was found in 19 (61%) of 31;samples from different sites. This is the same type that has dominated in pig tonsils, which suggests that to nsils may be the source of Y. enterocolitica contamination in the slaughter house. The four pulsotypes (1a, 4g, 6g, and 19q) found on edible offals wer e the same as those found in tonsils, which supports our hypothesis that to nsils are the contamination source for the liver, heart, and kidneys.