Campylobacter multi-locus sequence typing subtypes detected on chicken livers available at retail

Authors: Berrang, Mark; Meinersmann, Richard - Rick; Cox Jr, Nelson; Thompson, Tori

Submitted to: Journal of Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2018
Publication Date: 7/1/2018
Citation: Berrang, M.E., Meinersmann, R.J., Cox Jr, N.A., Thompson, T.M. 2018. Campylobacter multi-locus sequence typing subtypes detected on chicken livers available at retail. Journal of Food Protection. 81:101.

Interpretive Summary: Foodborne campylobacteriosis has been traced to undercooked chicken liver. It is not known what prevalence of Campylobacter to expect on fresh chicken livers available at retail. The objectives of this study were to measure prevalence of Campylobacter associated with chicken livers at retail and determine which subtypes are detected on the surface and inner tissue of livers. Fifteen packages of fresh chicken livers, each representing a unique combination of processing plant and sell by date, were collected at retail grocery stores. Three intact, undamaged livers per container (N=45) were selected and sampled, each by three methods: outside swab, inside swab accessed by pressing through a heat sterilized outer surface and whole liver by blending in enrichment broth. Each liver sample and one mL of exudate from each package was cultured for Campylobacter by plating on campy-cefex agar. The most prevalent Campylobacter colony type from each positive sample was subjected to whole genome sequencing and multi-locus sequence typing. Campylobacter was detected in at least one sample from every package. Surface swabs were positive for 29 of 45 livers; significantly fewer (P<0.01) swabs of internal tissue were positive at 14 of 45. Campylobacter was detected in 30 of 45 blended whole liver samples. Multiple subtypes were detected on five livers. In two cases, a different subtype predominated on the surface than internally. On one liver, three different subtypes were detected. A variety of subtypes of Campylobacter can be readily isolated from fresh retail chicken livers. Undercooked chicken livers pose a food safety risk.

Technical Abstract: Foodborne campylobacteriosis has been traced to undercooked chicken liver. It is not known what prevalence of Campylobacter to expect on fresh chicken livers available at retail. The objectives of this study were to measure prevalence of Campylobacter associated with chicken livers at retail and determine which subtypes are detected on the surface and inner tissue of livers. Fifteen packages of fresh chicken livers, each representing a unique combination of processing plant and sell by date, were collected at retail grocery stores. Three intact, undamaged livers per container (N=45) were selected and sampled, each by three methods: outside swab, inside swab accessed by pressing through a heat sterilized outer surface and whole liver by blending in enrichment broth. Each liver sample and one mL of exudate from each package was cultured for Campylobacter by plating on campy-cefex agar. The most prevalent Campylobacter colony type from each positive sample was subjected to whole genome sequencing and multi-locus sequence typing. Campylobacter was detected in at least one sample from every package. Surface swabs were positive for 29 of 45 livers; significantly fewer (P<0.01) swabs of internal tissue were positive at 14 of 45. Campylobacter was detected in 30 of 45 blended whole liver samples. Multiple subtypes were detected on five livers. In two cases, a different subtype predominated on the surface than internally. On one liver, three different subtypes were detected. A variety of subtypes of Campylobacter can be readily isolated from fresh retail chicken livers. Undercooked chicken livers pose a food safety risk.