The foodborne pathogen L. monocytogenes generally infects immunocompromised individuals, but cancer patients in particular are infected more frequently, with higher morbidity and mortality. Because of the known risk of L. monocytogenes, and other pathogens, in produce, immunocompromised individuals are often placed on neutropenic diets that exclude fresh produce. Therefore, this study aimed to first evaluate several kitchen-scale treatments as potential interventions to reduce the population of L. monocytogenes in prepared produce (apples, cucumbers, and celery), then develop a data-driven risk model for listeriosis in cancer patients who consume ready-to-eat (RTE) salads, as influenced by the kitchen-scale treatments. Surface blanching and surface blanching followed by peeling were the most effective treatments in both cucumbers (mean reductions of 5.1 and 5.9, respectively) and apples (mean reductions of 3.5 and 4.2 log cfu/g, respectively) (P < 0.05). All treatments lacked efficacy for celery, with reductions significantly less (P < 0.05) than in other products, likely due to considerable inoculum internalization. For refrigerated salads with no treatment, the median risk of invasive listeriosis over a period of one chemotherapy cycle was predicted to be at most 5.6 x 10-10. This decreased to 7.3 x 10-11 when salad components were surface blanched. Results from this study can be used to develop improved risk management strategies and risk communication materials for cancer patients and their caretakers.
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