Antimicrobial activity of cetylpyridinium chloride washes against pathogenic bacteria on beef surfaces

Cetylpyridinium chloride (CPC), a water-soluble, neutral pH, colorless compound, is widely used in oral hygiene products to inhibit bacteria responsible for plaque. Previously, researchers have demonstrated that CPC not only reduces Salmonella Typhimurium on poultry but also prevents cross-contamination. To determine the effectiveness of CPC against pathogens associated with lean and adipose beef surfaces, several spray-washing experiments (862 kPa, 15 s, 35 degrees C) with 1% (wt/vol) CPC were conducted. On lean beef surfaces, CPC immediately reduced 5 to 6 log(10) CFU/cm(2) of Escherichia coli O157:H7 and Salmonella Typhimurium to virtually undetectable levels (0 log(10) CFU/cm(2)), as well as after 35 days of refrigerated (4 degrees C), vacuum-packaged storage. On adipose beef surfaces, 5 log(10) CFU/cm(2) Salmonella Typhimurium and E. coli O157:H7 were reduced immediately (>2.5 log(10) CFU/cm(2)) with 1% CPC; by day 35 the reduction was <1.3 log(10) CFU/cm(2). Further plate overlay analyses indicated that the effectiveness of CPC against pathogens on adipose surfaces was not hampered by the presence of meat components or fatty acids. Additional chemical and microbiological analyses of 1% CPC-treated beef surfaces subjected to a secondary water wash (following contact times of 0, 5, 10, 15, or 30 min) or grinding did reduce pathogenic bacteria and CPC levels. However, residual CPC levels following any of the treatments were considered excessive for human consumption. Despite the residual levels, this study is the first to demonstrate the effect of CPC on pathogenic bacteria associated with beef surfaces immediately after treatment and also after long-term, refrigerated, vacuum-packaged storage.