Research Note: Evaluation of selected chlorhexidine salts/product and/or cetylpyridinium chloride as potential pre-slaughter crop disinfection agents using an in vitro assay simulating crop contents.

Salmonellae remain a prominent issue for poultry products regarding food safety. A predominant source of broiler carcass contamination at processing is from crop rupturing and subsequent contamination of the carcass during evisceration. Chlorhexidine (CHX) salts are commonly used in dental products for their antimicrobial capabilities. We evaluated CHX gluconate and CHX digluconate alongside cetylpyridinium chloride (CPC), a common disinfectant to test their antimicrobial properties and any possible synergistic effects between the two. These effects were evaluated using an in vitro assay simulating the crop contents of poultry. CHX digluconate, CHX gluconate, commercially available CHX gluconate and CPC were tested at 0.1 %, 0.2 %, 1 %, 1.8 %, and 2 %. Borosilicate tubes containing 2.5 g of chicken mash feed, pasteurized to remove unwanted bacteria, were used for assay. Pasteurized feed within tubes were suspended in CHX, CPC, CHX + CPC, or saline vehicle alone (control). Tubes were then inoculated with Salmonella Typhimurium (ST) (except non-inoculated controls) and allowed to statically incubate for 2 h at 37°C. Tube contents were then serially diluted for CFU enumeration. CHX and CPC, when used individually, demonstrated meaningful and significant (p < 0.05) reduction in ST recovery, especially at higher concentrations (1-2 %). Combinations of CHX + CPC at lower concentrations (0.1-0.2 %) were shown to have major antimicrobial effects and either reduced (p < 0.05) or eliminated ST recovery in this assay. These lower concentrations might be used for antemortem disinfection of crop contents prior to live haul at processing in future studies. In vivo efficacy may be affected by limitations on voluntary ingestion of drinking water during pre-slaughter feed withdrawal and was not evaluated in these studies.