Sampling by sponge wipe or skin excision for recovery of inoculated Salmonella and Campylobacter from defeathered broiler carcasses

Authors: Berrang, Mark; Cox Jr, Nelson; Oakley, Brian

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2013
Publication Date: 4/28/2014
Citation: Berrang, M.E., Cox Jr, N.A., Oakley, B. 2014. Sampling by sponge wipe or skin excision for recovery of inoculated Salmonella and Campylobacter from defeathered broiler carcasses. Journal of Food Protection. 77(5):824-827.

Interpretive Summary: Salmonella and Campylobacter are foodborne pathogens that have been associated with poultry and poultry meat. Chicken carcasses can become contaminated with Salmonella and Campylobacter during slaughter and processing. In order to provide a safe wholesome product, commercial processors and scientists work to determine which broiler processing steps may increase or decrease contamination. Towards this end, a repeatable method to determine the number of bacterial pathogens on carcasses would be useful. Some methods, such as cutting and removing skin, damage the carcass and cannot be done more than once on a single carcass. We compared a quick and easy, non-destructive sampling method using a sponge to a more time consuming and destructive skin removal (excision) method to measure how many Salmonella or Campylobacter cells we could recover from chicken carcasses. We found that skin excision was only marginally better at recovering Salmonella and Campylobacter than the sponge method. Furthermore, adding a skin excision step after using the sponge for a combination sampling method did not improve the efficacy of sponge sampling. Therefore, a sponge sample which does not damage the carcass and can be repeated on the same area of skin before and after processing steps is adequate to recover both Salmonella and Campylobacter. This non-destructive sampling method can be applied to measure the affect of various broiler processing steps on the microbiological quality of carcasses without loss of a saleable carcass. These data are useful to scientists, processors and regulatory agencies as they work to monitor microbiological quality of carcasses during processing.

Technical Abstract: Broilers may carry Salmonella and Campylobacter on inner and outer surfaces upon arrival at the slaughter plant and carcasses can be further contaminated during commercial processing. A sensitive, non-destructive, repeatable sampling method would be useful to test carcasses for levels of bacteria before and after specific processing steps to measure either contamination or efficacy of intervention techniques. Skin excision and blending are accepted as effective sampling methods to remove bacteria from skin, but requires damage to the carcass making repeated measurements on the same carcass difficult. Herein we compare sponge sampling to skin excision to recover inoculated Salmonella and Campylobacter from broiler carcasses. In each of three replications, broiler carcass breast skin was inoculated with approximately log 6.0 antibiotic resistant Salmonella and Campylobacter, allowed to dry for 60 s and sampled by either sponge, skin excision or sponge followed by skin excision. Marker Salmonella and Campylobacter were enumerated from all samples. Skin excision allowed recovery of 0.1 to 0.2 log more inoculated bacteria than did sponge sampling. When excision was used on the same skin previously sampled by sponging, the combination of both methods did not significantly improve recovery compared to sponging alone. Skin excision is marginally more sensitive than sponge sampling; however, for repeated nondestructive sampling of broiler carcasses during processing, sponge sampling is adequate to recover Salmonella and Campylobacter within 60 s of a contamination event.