L. monocytogenes survival on and transfer to surfaces in a melon packing shed environment

What is it about?

Cantaloupes have frequently been contaminated with bacterial pathogens and caused several high profile outbreaks over the years. In 2011, Rocky Ford cantaloupes contaminated with Listeria monocytogenes sickened 147 people and resulted in 33 fatalities, making it the deadliest foodborne outbreak in the U.S. in almost 90 years. Outbreak investigators determined that the packing shed where cantaloupes are washed and packaged was the most likely source of contamination for this outbreak. Our study investigated the potential for various surfaces used in a melon packing shed to support the survival of L. monocytogenes and the ability to transfer L. monocytogenes from a contaminated surface to a melon. Our results shows that soiled surfaces (surfaces that are unclean) supported significantly higher levels of L. monocytogenes contamination than clean surfaces. Also, water-absorbent materials like foam pads were more likely to contaminate cantaloupes then other commonly used conveyer belt surfaces (polyvinyl chloride, polyurethane, and nitrile rubber surfaces). The Rocky Ford variety of melons, implicated in the 2011 outbreak, were not more likely become contaminated than Athena variety melons. Soiled surfaces supported higher populations of L. monocytogenes than clean surfaces, and water-absorbent materials like foam pads are more likely to promote the transfer of L. monocytogenes to melons compared conveyor-belt materials. Our results indicate the surface cleanliness and surface type can affect the persistence and transfer of L. monocytogenes in the melon packing shed environment.

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Why is it important?

Cantaloupes have frequently been contaminated with bacterial pathogens and caused several high profile outbreaks over the years. In 2011, Rocky Ford cantaloupes contaminated with Listeria monocytogenes sickened 147 people and resulted in 33 fatalities, making it the deadliest foodborne outbreak in the U.S. in almost 90 years. Outbreak investigators determined that the packing shed where cantaloupes are washed and packaged was the most likely source of contamination for this outbreak. Our study investigated the potential for various surfaces used in a melon packing shed to support the survival of L. monocytogenes and the ability to transfer L. monocytogenes from a contaminated surface to a melon. Our results shows that soiled surfaces (surfaces that are unclean) supported significantly higher levels of L. monocytogenes contamination than clean surfaces. Also, water-absorbent materials like foam pads were more likely to contaminate cantaloupes then other commonly used conveyer belt surfaces (polyvinyl chloride, polyurethane, and nitrile rubber surfaces). The Rocky Ford variety of melons, implicated in the 2011 outbreak, were not more likely become contaminated than Athena variety melons. Soiled surfaces supported higher populations of L. monocytogenes than clean surfaces, and water-absorbent materials like foam pads are more likely to promote the transfer of L. monocytogenes to melons compared conveyor-belt materials. Our results indicate the surface cleanliness and surface type can affect the persistence and transfer of L. monocytogenes in the melon packing shed environment.