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Title: Multi-locus sequence subtypes of Campylobacter detected on the surface and from internal tissue of retail chicken livers

item Berrang, Mark
item Meinersmann, Richard - Rick
item Cox Jr, Nelson
item Thompson, Tori

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/18/2018
Publication Date: 8/23/2018
Citation: Berrang, M.E., Meinersmann, R.J., Cox Jr, N.A., Thompson, T.M. 2018. Multi-locus sequence subtypes of Campylobacter detected on the surface and from internal tissue of retail chicken livers. Journal of Food Protection. 81(9):1535-1539.

Interpretive Summary: Chicken liver is sometimes used to prepare lightly cooked liver pate dishes. There have been several outbreaks of human campylobacteriosis caused by undercooked chicken liver pate. It is not clear how prevalent Campylobacter is on the surface or within internal tissue of chicken livers at retail. We purchased fifteen containers of chicken livers from grocery stores and cultured both the external surface and internal tissue of forty-five livers for Campylobacter. When Campylobacter was detected, we used DNA sequence-based techniques to subtype the isolates. Campylobacter was detected in at least one sample from all 15 packages tested. Campylobacter was detected on the outside of 64% (29/45) of chicken livers and on the internal tissue of 31% (14/45). Generally, the Campylobacter subtypes detected had been previously reported as associated with human illness, chickens or both. A variety of Campylobacter can be found both externally and internally on chicken livers. Undercooked chicken liver poses a substantial food safety risk.

Technical Abstract: Foodborne campylobacteriosis has been traced to undercooked chicken liver. 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 0.1 mL of exudate from packages were 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 swabs of internal tissue were positive at 14 of 45 (P<0.01). Campylobacter was detected in 30 of 45 blended whole liver samples. Multiple subtypes were detected on eight livers. In four livers, 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.