Mitigating Prevalence and Persistence of L. monocytogenes using Novel Sanitation Strategies in Delis

<p>Ready-to-eat (RTE) deli meats sliced at retail are predicted to cause 83% of deli meat-associated listeriosis cases annually. While <em>L. monocytogenes </em>is commonly found in delis (55-90%), environmental prevalence varies by store (0-40%). Study 1 evaluated efficacy of 10 standardized SSOPs by testing 28 food and non-food contact surfaces for <em>L. monocytogenes</em> over 6 months in 30 retail delis. Intervention strategies employed in this study significantly decreased <em>L. monocytogenes</em>prevalence on FCS and NFCS in stores with moderate prevalence (0.5%, 0.8% reduction). However, we found that <em>L. monocytogenes</em> could persist despite implementation of SSOP control strategies. Study 2 assessed an aggressive 12 hour deep clean sanitation standard operating procedure (SSOP) in nine retail delis aimed to reduce persistent <em>Listeria monocytogenes.</em> The SSOP was executed by a trained professional cleaning service during a 12 hour shut-down. Delis (n=5) with historically low <em>L. monocytogenes </em>prevalence (300 samples tested) had no statistically significant changes in <em>L. monocytogenes</em>positive samples after the deep clean. In two delis with historically high <em>L. monocytogenes </em>prevalence (>10%), deep cleaning reduced <em>L. monocytogenes </em>positive samples by 50% and 75%; one deli had no change and one store had increased <em>L. monocytogenes</em> positive samples immediately post-deep clean. High prevalence delis returned to pre-deep clean <em>L. monocytogenes</em> prevalence levels within one month. Study 3 assessed the efficacy of a modified deep-clean SSOP conducted by store employees and complemented with training and facilities improvements to reduce <em>L. monocytogenes</em> prevalence. Fifty delis among 6 states were screened using a predictive logistic regression model that estimates the probability of high <em>L. monocytogenes</em> prevalence in a deli. Environmental samples (n=20) were collected immediately before, after, and once monthly for 6 months post-deep clean. Deep-cleans immediately reduced <em>L. monocytogenes </em>prevalence in 6 of 7 stores tested. A total of 22/139 (15.8%) samples before and 8/140 (5.7%) samples after deep-cleaning were positive for <em>L. monocytogenes,</em> a marginal mean decrease of 10.1 percentage points (CI95: -0.01, 21.0%; p=0.066) per store. Interventions reduced average monthly <em>L. monocytogenes</em> prevalence in each store by 9.7 percentage points (CI95: 2.50, 16.9%; p=0.017). Employee executed deep-cleans with training, education, and maintenance programs can reduce environmental <em>L. monocytogenes</em> prevalence, a pivotal part of preventing cross-contamination to RTE deli meats. Taken together, these studies underscore that improved sanitation strategies combined with facilities maintenance and improving food safety culture are pivotal to preventing listeriosis from RTE deli meats contaminated at retail.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Food Science

Year

2016

Author dc:creator

• Hammons, Susan Rose

Contributors dc:contributor

• Haley F. Oliver
• Bruce Craig
• Amanda Deering
• Jay Neal
• Manpreet Singh

• Biological sciences; Deep clean; Deli; Listeria; Retail; Sanitation
• Food Microbiology
• Food Science
• Microbiology

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/768

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-1960