Purpose: Our study aimed to determine if facility design and management practices affect L. monocytogenes prevalence in retail produce environments, which will subsequently inform intervention strategies to reduce L. monocytogenes.
Methods: We designed a comprehensive, 111 question survey to capture facilities, cleaning and sanitation frequencies, employee training, work shift arrangement, equipment usage, etc. Retail produce managers from 30 retail produce departments among seven states in the United States completed the survey in stores conducting monthly L. monocytogenes environmental sampling. Linear regression with Pearson correlation, ANOVA, and subsequent Tukey analyses were used to identify significant factors that impact L. monocytogenes prevalence (α=0.05).
Results: By Tukey comparison (α=0.05), presence of standing water near misted produce case drain covers (P=0.0125), increased time taken for cleaning after the produce preparing area has closed (P=0.0038), presence of a bottom shelf level that is inaccessible for cleaning, and holding dry produce (P=0.0217) significantly increased L. monocytogenes prevalence. Cleaning produce retail case food contact surfaces once every two to four days resulted in higher prevalence compared to once every four hours, once daily, and frequencies less than once per two weeks (P=0.0029). Changing gloves after handling each type of produce (P=0.0114), selecting role models among employees (P=0.0128), being aware of how gloves are managed (P=0.0015), and absence of traffic from the produce area to other departments during work (P=0.0394) strongly reduced prevalence. Counterintuitively, trafficking from deli to produce was associated with lower L. monocytogenes prevalence (P=0.0243).
Significance: This was the first study to investigate the impact of facility design and management practices on L. monocytogenes prevalence in retail produce environments. Verification of sanitation and management practices will identify additional risk factors.