Detection and prevalence of Listeria in US produce packinghouses and fresh-cut facilities

What is it about?

Listeria monocytogenes (LM) contamination of produce can often be traced back to the built environment of packinghouses and fresh-cut facilities. As there is limited information on the detection, prevalence, and distribution of this pathogen in produce operations, we developed and implemented environmental sampling plans for LM as well as other Listeria spp. in three packinghouses and five fresh-cut facilities in the United States. In each operation, routine sponge samples were collected over 1 year. Among a total of 2,014 routine sponge samples collected, LM prevalence varied from 0.8% to 5.8% for packinghouses and <0.4% to 1.6% for fresh-cut facilities. We also found that collection of multiple isolates is necessary to capture Listeria diversity present in produce operations. Finally, we found that 17/77 sponges that were positive for LM were positive at only one enrichment time indicating that LM testing after two different enrichment times provides enhanced sensitivity.

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