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United States Department of Agriculture

Agricultural Research Service

Title: Quantitative Assement of Hard Surface Disinfectant Activity Against the Food-Borne Pathogen, Listeria Monocytogenes

Authors
item Arnold, Judy
item Zambelli-Weiner, A - STERILEX
item Delaubenfels, A - STERILEX
item Kramer, S - STERILEX

Submitted to: Journal of Association of Official Analytical Chemists International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 2, 2006
Publication Date: November 30, 2006
Citation: Arnold, J.W., Zambelli-Weiner, A., Delaubenfels, A., Kramer, S. 2006. Quantitative assement of hard surface disinfectant activity against the food-borne pathogen, listeria monocytogenes. Journal of Association of Official Analytical Chemists International. 89:1-5.

Interpretive Summary: Listeria monocytogenes is an important bacterium that must be controlled to insure food safety. During the past two years, L. monocytogenes caused 20 deaths per 100 cases and was responsible for most food recalls for pathogen contamination. The objective of this work was to develop a method to accurately measure the disinfectant activity against L .monocytogenes. Standard methods for testing disinfectants against three bacteria are described in the Official Methods of Analysis of the Association of Official Analytical Chemists (AOAC) as use-dilution methods. No standard methods are provided for L. monocytogenes. In this study, the preliminary effect of a test compound was determined by measuring the minimum amount of the disinfectant required to kill 26 bacterial species. The size of the area killed on a culture plate ranged from 7.0 to 12.5 mm, and the smallest effective concentration ranged from 5 to 250 parts per million. For the final test, small stainless steel cylinders were contaminated with L. monocytogenes and tested separately for five, ten, and 15 minutes in disinfectant or phenol. After exposure, the cylinders were placed into two series of broth to neutralize the pH. The experiments were repeated three times with duplicate samples, and the disinfectant was more than three times as effective as phenol. This research presents a sensitive method that provides precise data for comparison and analysis of disinfectant activity against L. monocytogenes.

Technical Abstract: Listeria monocytogenes is an important food-borne pathogen that must be controlled to insure food safety. During the past two years, L. monocytogenes caused 20 deaths per 100 cases and was responsible for most food recalls for pathogen contamination. The objective of this work was to develop a quantitative method to assess disinfectant activity against L .monocytogenes. Standard procedures for testing disinfectants against three bacteria are described in the Official Methods of Analysis of the Association of Official Analytical Chemists (AOAC) as use-dilution methods. No standard methods are provided for L. monocytogenes. In this study, preliminary efficacy of a quaternary ammonium compound with hydroperoxide ion was determined by measuring the minimum inhibitory concentration for 26 bacterial species. The zones of inhibition ranged from 7.0 to 12.5 mm, and the minimum inhibitory concentration ranged from 5 to 250 ppm. For final efficacy, stainless steel carriers were contaminated with L. monocytogenes and tested separately for five, ten, and 15 minutes in disinfectant or phenol. After exposure, the carriers were placed into two series of D/E neutralization broth. For three replications with duplicate samples, the phenol coefficient was 3.3. This research presents a technique-sensitive method that provides quantitative data for comparison and analysis of disinfectant activity against L. monocytogenes.

Last Modified: 7/28/2014