Submitted to: International Symposium on Problems of Listeriosis
Publication Type: Abstract Only
Publication Acceptance Date: January 11, 2007
Publication Date: March 20, 2007
Citation: Berrang, M.E., Frank, J., Meinersmann, R.J. 2007. Effect of chemical sanitizers with and without ultra-sonication on Listeria monocytogenes as a biofilm within PVC drain pipes. International Symposium on Problems of Listeriosis. Mar. 20-23,2007. Savannah, GA. P12. Technical Abstract: Listeria monocytogenes (LM) can colonize poultry cooking plants becoming a long term resident. Once a processing plant is contaminated, LM can be readily detected in floor drains where it becomes part of a complex biofilm community. As part of this biofilm, LM is exceedingly difficult to eradicate with standard sanitizing protocols. The objective of these studies was to test the use of ultra-sonication in concert with chemical sanitizers to physically break up biofilm architecture in the drain allowing the chemical to contact LM cells directly. Pure culture LMs biofilms were created in model PVC drain pipes. Chemical sanitizers (based on chlorine, peroxide or quaternary ammonium) were applied to the drain pipes with and without a 30s ultra-sonication treatment. Controls with sterile water were included for comparison. LM cells were enumerated from the liquid in the drain and from the inside surface of the pipe. All chemicals lowered numbers of planktonic cells from 6.6 log cfu/ml in the water control to <100 cfu/ml. Attached cells were also affected by the chemical sanitizers. More than 6.0 log cfu were detected per cm2 of the inner surface of water control pipes; ultra-sonication did not result in a lower number recovered. Likewise, addition of ultra-sonication did not improve the performance of the peroxide based sanitizer. With or without ultra-sonication, the peroxide based sanitizer was effective to lessen the number of LM recovered from the surface resulting in approximately 2.0 log cfu/cm2. Both the chlorine and quaternary ammonium based sanitizers lowered the number of attached LM to a lesser degree resulting in 4.2 - 4.4 log cfu/cm2. However, addition of ultra-sonication improved the performance of both these sanitizers causing a further reduction to 3.1 and 2.9 cfu/cm2 for quaternary ammonium and chlorine based chemicals respectively. These results indicate that a peroxide based sanitizer alone can be very effective against biofilm LM in drain pipes while addition of ultra-sonication can improve the effectiveness of chlorine or quaternary ammonium sanitizers.