Salmonella in Chicken Bones and Neck Skin

November 2013

Poultry processors utilize chicken neck skin as a source of fat in ground chicken products. Bone-in and boneless chicken parts such as drumsticks, thighs, breasts, and wings are also used. Chicken neck skin and bones internalized with Salmonella are potential sources of the pathogen in ground chicken.

We conducted a study to determine the prevalence of Salmonella and serotype distribution in drumstick bones and neck skin of post-chilled chicken carcasses. One week prior to slaughter, chicken houses (n=26) at nine farms were tested for the presence of Salmonella using the boot sock method. Broiler flocks from these houses originated from Salmonella-positive breeders.

Eight Salmonella-positive chicken flocks and one flock with undetermined Salmonella-status were monitored through processing. Three hundred post-chilled drumsticks and 299 neck skin samples were randomly collected and analyzed for the presence of Salmonella. Skin samples were rinsed and stomached prior to analysis. Bones were extracted from the drumsticks and the external surface was sterilized. One Salmonella isolate from each sample was serogrouped. Half of the isolates representing different sample types was serotyped.

The overall Salmonella prevalences in drumstick bones, neck skin, and farms were 0.8, 21.4, and 80.1%, respectively. Prevalences on rinsed skin samples (4.0%) and stomached skin samples (24.1%) were significantly (P < 0.05) different. Prevalences of serogroups B, C2, D, and E were 23.4, 31.9, 11.7, and 29.8%, respectively. Serogroup C2 was the only Salmonella serogroup detected in bone marrow and it was the most common serogroup (31.3%) among the farm isolates. Serogroup E was the most prevalent (40%) among neck skin isolates.

Across all samples, six Salmonella serotypes (Kentucky, Liverpool, Typhimurium, Enteritidis, Agona, and Ouakam) were identified. Salmonella Liverpool (37.9%), S. Kentucky (27.6%), and S. Typhimurium (27.6%) were isolated most frequently from neck skin. The two bone isolates were S. Kentucky. Over 50% of the farm isolates were S. Kentucky and S. Ouakam.

Approximately 25% of the neck skin samples were Salmonella-positive, indicating a significant risk of including skin in ground chicken production. S. Kentucky is not a common serotype causing salmonellosis in the U.S. The presence of this serotype in drumstick bones, coupled with its low prevalence, indicate that virulent Salmonella originating from bones is likely to be low in ground chicken.