T2-09 Evaluation of Deep Cleans in Retail Delis as a Listeria monocytogenes Control Strategy

Monday, July 29, 2013: 11:00 AM
213D (Charlotte Convention Center)
Susan Hammons, Purdue University, West Lafayette, IN
Thomas Ford, Ecolab Inc., Greensboro, NC
Michael Howard, Ecolab Inc., Greensboro, NC
Jingjin Wang, Purdue University, West Lafayette, IN
Haley Oliver, Purdue University, West Lafayette, IN
Introduction: Delicatessen meats sliced at retail are estimated to cause 83% of listeriosis cases resulting from consumption of contaminated deli meat annually. Previously tested daily SSOPs by our group did not reduce Listeria monocytogenes (LM) contamination in delis with evidence of highly prevalent and persistent LM contamination thus warranting alternative aggressive mitigation strategies. 

Purpose: The purpose of this study was to assess the efficacy of an aggressive twelve hour deep clean SSOP aimed to reduce persistent LM environmental contamination in retail delis. 

Methods: We tested the efficacy of a deep clean SSOP in nine delis in three states. The developed SSOP protocol combined Food Marketing Institute recommended daily SSOPs and input from experts in Listeriacontrol from food manufacturing and sanitation. The SSOP was executed by a trained professional cleaning service during a 12 hour shut-down period. A modified BAM protocol was used to detect LM in 28 food and non-food contact surfaces samples taken immediately before and after each cleaning, and in samples taken monthly for 3 months.

Results: Delis (n = 5) with historically low LM prevalence (<5% samples; >300 samples tested) had no statistically significant changes in LM positive samples after the deep clean. Deep cleans in four delis with historically high LM prevalence (≥10%) had varying efficacy. In two delis, deep cleaning reduced LM positive samples by 50% and 75%; one deli had no change and one store had increased LM positive samples immediately post-deep clean. LM positive samples returned to pre-deep-clean levels in highly prevalent delis based on monthly sampling.

Significance: Deep cleaning delis can be immediately effective in delis with high LM prevalence and persistence and do not increase LM prevalence in stores with historically low LM prevalence. However, a single deep clean may not be sufficient to mitigate LM in some retail delis with evidence of persistence.