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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR CHARACTERIZATION AND GASTROINTESTINAL TRACT ECOLOGY OF COMMENSAL HUMAN FOOD-BORNE BACTERIAL PATHOGENS IN THE CHICKEN

Location: Poultry Microbiological Safety Research

Title: Comparison of neck skin excision and whole carcass rinse sampling methods for determining Salmonella prevalence and E. coli counts on broiler carcasses before and after immersion chilling

Authors
item COX, NELSON
item Richardson, Larry
item Cason Jr, John
item BUHR, RICHARD
item Vizzier-Thaxton, Y -
item Smith, D -
item Cray, Paula
item Romanenghi, C -
item Pereira, L V -
item Doyle, M -

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 13, 2010
Publication Date: May 1, 2010
Citation: Cox Jr, N.A., Richardson, L.J., Cason Jr, J.A., Buhr, R.J., Vizzier-Thaxton, Y., Smith, D.P., Cray, P.J., Romanenghi, C.P., Pereira, L.B., Doyle, M.P. 2010. Comparison of neck skin excision and whole carcass rinse sampling methods for determining Salmonella prevalence and E. coli counts on broiler carcasses before and after immersion chilling. Journal of Food Protection. 73(5):976-980.

Interpretive Summary: The implementation of Hazard Analysis Critical Control Point (HACCP) and similar systems in poultry processing has led to an increase in microbiological sampling of poultry carcasses. As the world becomes a global market for the exchange of foods, many countries are developing microbiological criteria that may or may not be science based. Some countries have established or are considering the establishment of Salmonella “free” raw poultry criteria. The considerable variations in sensitivity observed between sampling procedures used to set these criteria have not been fully elucidated. The purpose of this study was to evaluate two sampling procedures (whole carcass rinse and neck skin excision) for Salmonella and E. coli recovery from individual poultry carcasses. Overall, no significant differences were observed between the two methods for Salmonella prevalence. Both methods produced false negatives which could potentially hinder any effort to standardize one particular method globally. If a sensitive and accurate sampling method could be used, this would help to produce harmonization when trying to evaluate prevalence data between countries. However, sample type is not the only concern as the methodology procedures used in the laboratory must also be harmonized to generate accurate and reliable data for Salmonella prevalence comparison on poultry carcasses between sampling methods.

Technical Abstract: A regulatory agency (FSIS) in the U.S. rinses whole broiler carcasses with 400 ml of 1% buffered peptone water (BPW) for Salmonella detection, while the European Union (EU) samples a 25g composited neck skin from three carcasses. The purpose of the study was to evaluate the FSIS and EU procedures for Salmonella and E. coli recovery from the same poultry carcass. Carcasses were obtained from three poultry processing plants in three states. For all three plants, two replications of 30 broiler carcasses each were obtained just prior to the inside-outside bird washer (IOBW) and two replications of 30 broiler carcasses each were obtained just after immersion chilling. The skin around the neck area was aseptically removed and bagged separately from the carcass and microbiological analysis performed. Neck skin (8.3 g) was weighed aseptically, added to 83 ml of sterile BPW and stomached for 30 sec. The corresponding carcass was bagged along with 400 ml BPW, shaken for 1 min, 30 ml of the 400 ml of whole carcass rinsate (WCR) removed, and added to an additional 30 ml of sterile BPW. Aliquots were then removed from each sample and plated onto Petrifilm® for E. coli/coliform enumeration. The neck skin with BPW (NS) and WCR were incubated for 24 h at 37°C. After incubation, standard FSIS Salmonella cultural procedures were performed for both sampling methods. Overall, carcasses obtained at the IOBW had significantly greater (P<0.05) E. coli counts with the WCR (log10 2.9 cfu/ml) compared to the NS sample (log10 2.4 cfu/ml). A significant difference was observed from post-chill carcasses between WCR (log10 0.65 cfu/ml) and NS (log10 0.14 cfu/ml). A significant difference in Salmonella prevalence was not observed between the two sampling procedures. Pre-chill, 37% (66/180), 28% (50/180), and 51% (91/180) of carcasses were Salmonella positive by WCR, NS, and both procedures combined, respectively. Post-chill, 3% (5/177), 7% (12/177), and 10% (17/177) of the carcasses were Salmonella positive by the WCR, NS, and combination of both procedures, respectively. The carcass sampling procedure used by U.S. and EU both performed similarly for Salmonella prevalence determination. However, both procedures resulted in false negatives which indicate a lack of sensitivity.

Last Modified: 9/10/2014
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