Sanitizer efficacy against Escherichia coli O157:H7 biofilms on inadequately cleaned meat-contact surface materials

Abstract

This study evaluated the efficacy of various sanitizers against Escherichia coli O157:H7 cells in biofilms formed on surface materials used in beef fabrication facilities. Coupons (2×5 cm) of stainless steel, acetal, and high-density polyethylene were inoculated (3-4 log CFU/cm2) with rifampicinresistant £ coli 0157:H7 (6-strain mixture) and incubated at 15°C in an unsterilized beef fat-lean tissue homogenate (pH 5.66). After 3 days of incubation, attached cells were challenged (for I or 10 min) by submerging coupons in minimum and maximum recommended concentrations of each of seven sanitizing solutions or distilled water (control). Sanitizer treatments reduced £ coli 0157:H7 on coupons by 0.0 to 2.2 log CFU/cm2, and treatment efficacy decreased in the order acidified sodium chlorite > peroxyacetic acid > potassium peroxy monosulfate/sodium chloride = peroxyacetic acid/octanoic acid mixture (PA/OA) > cetylpyridinium chloride > quaternary ammonium chloride compound mixture (QACC) = sodium hypochlorite (SH) = water control. Pathogen reductions generally increased as sanitizer concentration and exposure time increased.The influence of biofilm age (0,3 and 7 days incubation at 15°C) on sanitizer (SH, QACC and PA/OA) efficacy was evaluated in a separate experiment; results showed that £ coli 0157:H7 biofilm cells became less sensitive to most sanitizer treatments as biofilm age increased. Surface material did not (P ≥ 0.05) influence the fate of biofilm cells during sanitizing treatments. While no sanitizer consistently reduced pathogen populations by more than 2.2 log cycles on soiled surfaces, approved concentrations of acidified sodium chlorite and peroxyacetic acid-based sanitizers may be more effective than other sanitizers against £ coli O157:H7 on inadequately cleaned surfaces.