Survival and growth of Listeria monocytogenes on whole cantaloupes is dependent on site of contamination and storage temperature

What is it about?

Listeria monocytogenes is a bacterial foodborne pathogen that has been associated with a number of food commodities (deli meats, soft cheeses, and cantaloupes). In 2011, one of the deadliest outbreaks in U.S. history occurred when individuals consumed ‘Rocky Ford’ cantaloupes contaminated with L. monocytogenes, which resulted in 29 deaths and 147 hospitalizations. Our research here examined the survival of L. monocytogenes on different varieties (‘Rocky Ford’ and ‘Athena) of cantaloupes to stored at different temperatures to determine which factors influence L. monocytogenes growth on cantaloupe surfaces. Our work found that when cantaloupes were stored at 25oC, L. monocytogenes can grow on the ‘stem scar’ area (where the vine of the plant attaches to the melon). Similarly, at lower storage temperature (4 and 10oC), L. monocytogenes populations were stable on the stem scar. In contrast, populations of L. monocytogenes did not survive well on the cantaloupe rinds at all, declining at all three storage temperatures evaluated. We also did not find differences in survival of L. monocytogenes on Rocky Ford and Athena cantaloupes. In conclusion, the specific site of cantaloupe contamination and storage temperature influence the growth and survival of L. monocytogenes, regardless of the cultivar evaluated.

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