SKIN ATTACHMENT MODEL FOR IMPROVED LABORATORY EVALUATION OF POTENTIALCARCASS DISINFECTANTS FOR THEIR EFFICACY AGAINST SALMONELLA ATTACHED TO BROILER SKIN

An improved laboratory system for testing the efficacy of potential br oiler carcass disinfectants against attached Salmonella was developed. Breast skin from freshly processed chilled broilers was cut into 10 c m diameter pieces, irradiated to inactivate vegetative microflora and served as the attachment surface. Salmonella typhimurium and Salmonell a montevideo were grown in brain heart infusion (BHI) broth at 23 or 3 7 degrees C, diluted in 0.1 M potassium phosphate buffer (KPB), and in oculated onto skin samples as a coarse aerosol spray. At 10, 20 or 30 min post inoculation, skins were vigorously rinsed twice with phosphat e buffer (PB) to remove ''loose'' cells. To enumerate salmonellae rema ining on the skin (''attached'' cells), skins were blended with fresh PB and plated onto tryptic soy agar (TSA). Applying 10(2), 10(3) or 10 (4) cells/skin consistently resulted in attachment of 23 to 44% of the applied inoculum. Culturing temperature and serotype did not affect a ttachment. The described skin attachment model (SAM) provides a reliab le and repeatable procedure for studying the efficacy of various treat ments for removing or inactivating enteropathogens that are attached t o poultry skin. The SAM allows for consistency in testing of antimicro bial agents against attached bacteria and enables utilization of speci fic bacteria without interference from background microflora using non -selective recovery techniques.