Filter sterilized carcass rinsate for recovery of Salmonella species in various concentrations of cetylpyridinium chloride

Authors: Cosby, Douglas; Berrang, Mark; Frye, Jonathan; Hinton Jr, Arthur

Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2023
Publication Date: 5/7/2023
Citation: Cosby, D.E., Berrang, M.E., Frye, J.G., Hinton Jr, A. 2023. Filter sterilized carcass rinsate for recovery of Salmonella species in various concentrations of cetylpyridinium chloride. Journal of Food Safety. 10.1002/fsn3.3463.
DOI: https://doi.org/10.1002/fsn3.3463

Interpretive Summary: Salmonella recovery continues to be a concern to regulatory personnel. This study used carcasses from a local processor and rinsed according to USDA-FSIS protocol with buffered peptone water. The rinsate was collected, pooled into one container and filter sterilized to prevent overgrowth with normal bacterial flora during the antimicrobial resistance testing. Various concentrations of cetylpyridinium chloride, a commonly used biocide, were placed into 24 well tissue culture plates and inoculated, individually, with 10 common Salmonella serotypes commonly isolated from poultry products. The results indicate that variation occurred across the 10 serotypes and implies that various compounds in the carcass rinse might alter the survival of the Salmonella during storage, allowing potentially more virulent strains to survive.

Technical Abstract: Controlling Salmonella in poultry processing continues to be important to processors and consumers. Cetylpyridinium chloride (CPC) has proven to be effective in vitro in the controlling Salmonella. This study evaluated the recovery of Salmonella after overnight storage in 4 C filter-sterilized carcass rinsate containing CPC from 0.5 to 1000 ppm (µg/mL). Ten Salmonella serotypes, isolated from poultry products, were grown in Bacto-Tryptic Soy Broth overnight at 37oC. Serial dilutions of a CPC/propylene glycol solution were prepared in 24-well tissue culture plates containing filter-sterilized carcass rinsate. Approximately 107 cfu/mL of each Salmonella serotype was added to the appropriate wells. Inoculated plates were stored overnight at 4 C. After storage, triplicate plates of brilliant green agar with sulfapyridine agar were surface inoculated with 10 µL of the contents for each well, streaked for isolation and incubated at 37 C for 24 hrs. Three replications were conducted. Presence of typical colonies on BGS plates was recorded as growth and verified through biochemical and serological testing. Of the serotypes chosen, Salmonella Kentucky, Dublin and Enteritidis were the least resistant to CPC with a median minimum inhibitory concentration (MIC) of 15.63 µg/mL (range from 3.91 to 62.50 µg/mL); S. Typhimurium demonstrated a median MIC of 125.00 µg/mL (range from 31.25 to 125.00 µg/mL). Residual CPC potentially remaining attached to a carcass or in the weep after processing could potentially change the Salmonella serotype recovered from carcass rinses during regulatory testing, with potential more virulent strains not recovered.