The prevalence of Listeria spp. in the skins of poultry legs (drumsticks), wings, and whole livers, representing 160 packages, three national brands, and purchased from three supermarkets in Davis, California was investigated first. Overall, Listeria spp., L. monocytogenes, L. innocua, and L. welshimeri were present in 40.6, 13.1, 26.3, and 1.3% of the chicken parts. For L. monocytogenes spp. the overall prevalence in the skins of wings, drumsticks, and livers was 10, 15, and 14% and varied extensively with sampling day. Next, we evaluated the presence of Listeria spp. in 12 locations and products collected from a slaughterhouse during four visits. A total of 188 samples were analyzed. No Listeria spp. were isolated from feathers (5 g composite sample from 10 birds), scalding tank water overflow (25 ml), chiller incoming water (25 ml), neck skin (5–9 g), whole liver after chilling, and cecum and large intestine content (1 g) samples. Listeria spp. were present in 18.8% of feather picker drip water (25 ml), 12.5% of chiller water overflow (25 ml), 37.5% of recycling water for cleaning gutters (25 ml), 25% of hearts, and 31.3% of mechanically deboned meat samples (25 g). The prevalence of L. monocytogenes in packaged livers and skins of drumsticks and wings at the end of the processing line was 33.3, 36.7, and 70.0%, respectively. After 4 d storage of the same packages at 4°C, L. monocytogenes was recovered from 40, 52, and 72% of the respective products. The prevalence of L. monocytogenes on the hands and gloves of the persons hanging birds after chilling, cutting carcasses, and packaging parts was 20, 45.5, and 59%. respectively. Overall, the study demonstrated the high prevalence of Listeria spp. and L. monocytogenes in poultry products and, that through certain improvements and innovations at the slaughterhouse level, contamination with Listeria can be minimized.

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Author notes

1Present address: Departmento de Patologia Animal l (Sanidad Animal) U.D. Microbiolgia e Immunologia. Facultad de Veterinaria Universidad Complutense 28040 Madrid, Spain.