Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2008
Publication Date: 1/1/2009
Citation: Hunter, S.M., Berrang, M.E., Meinersmann, R.J., Harrison, M. 2009. Genetic diversity of campylobacter on broiler carcasses collected preevisceration and postchill in 17 U.S. poultry processing plants. Journal of Food Protection. 72(1):49-54. Interpretive Summary: Campylobacter is an important human pathogen that is commonly associated with poultry and poultry meat. Campylobacter generally enters the processing plant on live broilers. Processing is very effective and processed carcasses have far fewer numbers of Campylobacter. It is, however, unclear how broiler processing affects Campylobacter diversity as measured by number of subtypes present on carcasses. Change in diversity during processing could be due to cross contamination from processing equipment, destruction of subtypes that are susceptible to the stresses associated with processing or selective survival of subtypes that are more suited to survive processing stresses. Flocks of broilers were sampled at two sites in each of 17 U.S. commercial processing plants. Carcasses were collected early in processing (prior to evisceration) and again as fully processed chilled carcasses. Campylobacter isolates (1,249) from 417 carcasses were subtyped by a DNA sequencing method. Overall, diversity of Campylobacter present on fully processed carcasses was lower than that observed on carcasses prior to evisceration. Some subtypes were found only on pre-eviscerated carcasses and others only on fully processed carcasses. These data show that processing lessens the diversity of Campylobacter on broiler carcasses, and some subtypes are more suited to survive processing than others. Characterization of subtypes that survive processing will be useful in future efforts to design effective intervention strategies.
Technical Abstract: Campylobacter jejuni and C. coli are the most important human enteropathogens among the campylobacters. The objective of this study was to determine how diversity in Campylobacter found on chicken carcasses collected from 17 broiler processing plants in the United States is impacted by processing. Genetic diversity was determined from up to four isolates per carcass, by sequencing the Short Variable Region of the flaA locus. On seventy percent of Campylobacter positive carcasses all isolates were indistinguishable by flaA-SVR typing. The genetic diversity of Campylobacter decreased as carcasses proceeded through processing; carcasses sampled early in processing (re-hang) had significantly more genetic diversity in Campylobacter populations than carcasses sampled post-chill. Certain types of Campylobacter were found only at re-hang and not at post-chill. Other subtypes were found at post-chill and not at re-hang. These data suggest that some subtypes may be prone to perish during processing while others survive or persist despite stressors encountered with processing and its environment.