Characteristics and practices that may lead to Listeria monocytogenes contamination in retail delis

Wang, Jingjin. M.S., Purdue University, May 2014. Characteristics and Practices that May Lead to Listeria monocytogenes Contamination in Retail Delis. Major Professor: Haley F. Oliver. The foodborne pathogen, Listeria monocytogenes, can contaminate ready-to-eat (RTE) deli meats at retail delis, since retail delis provide an ideal environment for L. monocytogenes growth. Current risk assessment indicates that 83% of listeriosis cases from RTE deli meats are all from RTE deli that are sliced at retail delis. Strategies for controlling L. monocytogenes in retail establishments are essential to prevent postprocessing contamination of RTE foods. In order to determine the potential risk factors associated with L. monocytogenes contamination and develop best practices to reduce L. monocytogenes, we sampled the retail establishment environment, isolated L. monocytogenes, and conducted a Store Characteristics Survey analysis among 85 retail deli establishments. L. monocytogenes prevalence was higher on non-food contact than food contact surfaces. Several practices implemented in retail delis were shown to be risk factors for L. monocytogenes cross-contamination. For example, handling raw meat near deli area, low numbers of slicers designated to slice deli meats, and all sanitizers not properly applied were associated with high L. monocytogenes prevalence (p < 0.05).