Effect of Cleaners and Sanitizers on Listeria monocytogenes Attached to Product Contact Surfaces.

A variety of chemical cleaning and sanitizing compounds were evaluated for their ability to remove and/or inactivate surface adherent Listeria monocytogenes . Adherent cells were obtained by incubating 1-cm2 chips of stainless steel or plastic conveyor belts with a multistrain cocktail of L. monocytogenes for 24 h at 25°C. Resistance of adherent cells to sanitizers was dependent upon the surface studied, being greatest on polyester/polyurethane followed by polyester and stainless steel. Biofilm removal with cleaners followed the same pattern as sanitizers with the polyester/polyurethane surface being most difficult to clean. Complete biofilm removal and/or inactivation was obtained in many cases where the surface was first cleaned prior to exposure to sanitizer. The data support conventional wisdom in that cleaning must precede sanitizing in order to remove and inactivate microorganisms. Listeria biofilms should be controllable by combining Good Manufacturing Practices with the discipline of a Hazard Analysis Critical Control Point Program.