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

Controlling Salmonella in poultry processing continues to be important to processors and consumers. Cetylpyridinium chloride (CPC) has proven to be effective in vitro in controlling Salmonella. This study evaluated the recovery of Salmonella after overnight storage in 4°C filter‐sterilized carcass rinsate containing CPC from 0.44 to 909 ppm (μg/mL). Ten Salmonella serotypes (18 strains), of which 6 serotypes are commonly isolated from poultry products, were grown in Bacto‐Tryptic Soy Broth overnight at 37°C. Serial dilutions of a CPC/propylene glycol solution were prepared in 24‐well tissue culture plates containing filter‐sterilized carcass rinsate. Approximately 10(7) 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 (BGS) were surface inoculated with 10 μL of the contents for each well, streaked for isolation, and incubated at 37°C for 24 h. Three replications were conducted. The 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 14.22 μg/mL (range from 3.55 to 56.88 μg/mL); S. Typhimurium demonstrated a median MIC of 114.00 μg/mL (range from 28.44 to 114.00 μg/mL). Residual CPC potentially remaining attached to a carcass or in the weep after processing could potentially alter which Salmonella serotype is recovered from a carcass rinse due to different growth patterns during regulatory testing, with a potential for more virulent strains not to be recovered.