Assessing Listeria Monocytogenes Contamination Risk Using Predictive Risk Models and Food Safety Culture Management in Retail Environments

Retail environments are critical transmission points for Listeria monocytogenes to humans. Past studies have shown L. monocytogenes contamination varies widely across retail environments. L. monocytogenes can transmit among environmental surfaces and subsequently from environment to food via cross-contamination. Modified SSOPs (sanitation standard operating procedures) have been shown to have limited impact on reducing L. monocytogenes prevalence in retail deli environments. Food safety culture and climate, such as beliefs, values, and hygiene behaviors, have been identified as factors impacting food safety performance and microbial outputs. Handwashing and its compliance are among the most prominent personal hygiene aspects subjected to investigation in the past decade, illustrating hygiene behavior as a risk factor and an important consideration to ensure food safety. Additionally, effective management and welldesigned infrastructure, such as vertical and lateral communication, employees’ training, accountability, and equipment designed to prevent cross-contamination, have also been described as critical contributors to a sustainable food safety program. However, given such a deadly foodborne pathogen as L. monocytogenes, the correlation between food safety culture and its prevalence remains unknown. We hypothesized that there was a relationship among food safety culture management, infrastructure, and L. monocytogenes prevalence at retail. Our goal is to identify additional risk factors on L. monocytogenes control, develop feasible recommendations, and direct resources to enhance food safety. In the present dissertation, we developed and implemented a predictive risk model, along with employee- and management-implemented SSOPs, in 50 deli establishments across six U.S. states to evaluate and control L. monocytogenes contamination risk and prevalence (Chapter 2). The predictive risk model, based on logistic regression, uses five environmental sites to predict L. monocytogenes prevalence in the entire deli environment. It identified 13 high-risk stores, seven of which were confirmed during subsequent monthly sampling. We found that deep clean intervention reduced L. monocytogenes prevalence on non-food contact surfaces both immediately after the intervention and during follow-up, with marginal significance (αadj=0.0125). The employee- and management-implemented deep clean can control L. monocytogenes prevalence in retail delis; the predictive risk model, though conservative, will require further validations and can be useful for surveillance purposes. Complementary to the above study, we tackled the L. monocytogenes challenge via food safety culture and climate approach (Chapter 3). Concurrently to the monthly environmental sampling, we distributed food safety culture and climate survey to the 50 stores, with one manager and up to five associates from each establishment, over a 12-month period and overlapped with before, after, and follow-up deep clean. We found that stores with lower L. monocytogenes contamination risk had better food safety culture, including greater sense of commitment to food safety program (padj=0.0317) and more complete training (padj=0.0117). Deep clean improved managers’ (padj=0.0243) and associates’ (padj=0.0057) commitment to food safety. This study indicates that food safety culture and climate are crucial component in building a viable, sustainable food safety program. Another survey tool was used to evaluate infrastructure designs, management strategies, and sanitation practices in relation to L. monocytogenes control in retail produce environments (Chapter 4). We distributed the survey to 30 retail produce departments across seven U.S. states. Hand hygiene, minimizing cross-contamination, and maximizing equipment cleanability were the most prominent factors in L. monocytogenes control

Maturing Food Safety Culture with Nudging in Food Manufacturing Environments in the UK

Introduction: A recent surge in including food safety culture in various public guidelines and private standards, such as GFSI benchmarking standards 2020, Codex HACCP Principles and Guidelines, EU legislation, and FDA Food Safety Blueprint 2020, has prompted global interest and challenged industry to drive evidence-based cultural change. The nudge theory is effective in influencing people’s behaviours and shaping culture, embraced worldwide in various initiatives – but no empirical study on its adoption in food safety culture context. Purpose: This research study aims to improve food safety culture via nudging in a weekly change cycle using a validated machine learning tool. Methods: Each person was nudged every day through answering one question on food safety in nine UK food manufacturing companies (13 sites) from June 2021 to September 2022, resulting in over 180,000 answers. Machine learning generated a weekly action report for each company, from which the companies picked one incremental action to execute every week. Culture maturity was calculated as the running average of all responses; ANOVA and logistic regression were conducted to determine how culture of food safety changed through nudging and to identify key drivers of change. Results: Using the GFSI food safety culture position paper, companies have varying strengths on the five dimensions. Heatmap analysis indicates that “Adaptability” is the least mature dimension and “People” the second least mature. “Values and Mission” is the most mature in the participating companies, although how and why food safety was prioritised during business-critical decision-making was not always shared with team members. In the course of 16 months, nudging leads to improvement in food safety culture in several of the companies. Significance: This study contributes to the currently scarce empirical evidence on how culture of food safety is improved. It is also the first study to use nudging to improve food safety culture

Hydrogen peroxide and sodium hypochlorite disinfectants are more effective against Staphylococcus aureus and Pseudomonas aeruginosa biofilms than quaternary ammonium compounds

Abstract Background Antimicrobial disinfectants are used as primary treatment options against pathogens on surfaces in healthcare facilities to help prevent healthcare associated infections (HAIs). On many surfaces, pathogenic microorganisms exist as biofilms and form an extracellular matrix that protects them from the antimicrobial effects of disinfectants. Disinfectants are used as all-purpose antimicrobials though very few specifically make biofilm efficacy claims. The objective of this study was to evaluate the efficacy of eight registered disinfectants (six registered by the Environmental Protection Agency and two products registered in by the European Chemical Agency) with general bactericidal claims, but currently no biofilm efficacy claims, against Staphylococcus aureus ATTC-6538 and Pseudomonas aeruginosa ATCC-15442 biofilms. We hypothesized that hydrogen peroxide and sodium hypochlorite disinfectant products would be more effective than quaternary ammonium chlorides. Methods This study tested the bactericidal efficacy of eight registered disinfectant products against S. aureus ATCC-6538 and P. aeruginosa ATCC-15442 grown on glass coupons using a Center for Disease Control (CDC) biofilm reactor and EPA MLB SOP MB-19. Bactericidal efficacy was determined after treating coupons with disinfectants following standard EPA MLB SOP MB-20. Results Overall, sodium hypochlorite and hydrogen peroxide disinfectants had significantly higher bactericidal efficacies than quaternary ammonium chloride disinfectants. We also found that all tested disinfectants except for quaternary ammonium chloride disinfectants met and exceeded the EPA standard for bactericidal efficacy against biofilms. Conclusion In general, bactericidal efficacy against biofilms differed by active ingredient. The efficacies of sodium hypochlorite and hydrogen peroxide disinfectants did not vary between strains, but there were significant differences between strains treated with quaternary ammonium chloride disinfectants

Comparative genomics of the genus Roseburia reveals divergent biosynthetic pathways that may influence colonic competition among species

Roseburia species are important denizens of the human gut microbiome that ferment complex polysaccharides to butyrate as a terminal fermentation product, which influences human physiology and serves as an energy source for colonocytes. Previous comparative genomics analyses of the genus Roseburia have examined polysaccharide degradation genes. Here, we characterize the core and pangenomes of the genus Roseburia with respect to central carbon and energy metabolism, as well as biosynthesis of amino acids and B vitamins using orthology-based methods, uncovering significant differences among species in their biosynthetic capacities. Variation in gene content among Roseburia species and strains was most significant for cofactor biosynthesis. Unlike all other species of Roseburia that we analysed, Roseburia inulinivorans strains lacked biosynthetic genes for riboflavin or pantothenate but possessed folate biosynthesis genes. Differences in gene content for B vitamin synthesis were matched with differences in putative salvage and synthesis strategies among species. For example, we observed extended biotin salvage capabilities in R. intestinalis strains, which further suggest that B vitamin acquisition strategies may impact fitness in the gut ecosystem. As differences in the functional potential to synthesize components of biomass (e.g. amino acids, vitamins) can drive interspecies interactions, variation in auxotrophies of the Roseburia spp. genomes may influence in vivo gut ecology. This study serves to advance our understanding of the potential metabolic interactions that influence the ecology of Roseburia spp. and, ultimately, may provide a basis for rational strategies to manipulate the abundances of these species