Infrastructure, sanitation, and management practices impact Listeria monocytogenes prevalence in retail grocery produce environments

Abstract

We designed and implemented a comprehensive survey of facilities, management practices, and cleaning and sanitizing frequencies in 30 United States grocery retail produce departments to evaluate Listeria monocytogenes control strategies. Produce department managers completed the survey during a six-month longitudinal study of L. monocytogenes on food and non-food contact surfaces in retail produce departments. L. monocytogenes prevalence in each store was compared to survey responses both overall and by surface type. Pearson correlation and ANOVA were used to identify significant survey variables associated with L. monocytogenes prevalence. Tukey pairwise comparisons were conducted to elucidate the nature of significant effects (α = 0.05). Pooled water near misted produce case drain covers and lack of disposable glove changing oversight after touching non-food-contact surfaces (NFCS) significantly correlated with higher L. monocytogenes prevalence overall (p = 0.01, p = 0.002), on food-contact surfaces (FCS; p = 0.001, p = 0.01) and NFCS (p = 0.04, p = 0.003). Cleanability of bottom dry produce shelf, changing gloves after handling each type of produce, and selecting lateral role models among employment strongly correlated with lower L. monocytogenes prevalence overall (p = 0.02, p = 0.01, p = 0.01) and on NFCS (p = 0.02, p = 0.011, p = 0.01). Mixed results were found regarding inter-departmental traffic and cleaning time and frequency. General linear regression demonstrated a notable effect by 7 predictor variables synergistically upon L. monocytogenes prevalence (p = 0.0001 for overall, p = 0.0007 for FCS, p = 0.001 for NFCS). This is the first study to investigate the impact of facility design and management practices on L. monocytogenes prevalence in retail produce environments.