FDA Reports Factors Potentially Contributing to Cantaloupe Listeria Outbreak

On October 19, 2011, FDA released a document which provides an overview of factors that potentially contributed to the contamination of fresh, whole cantaloupe with the pathogen Listeria monocytogenes, which was implicated in the 2011 multi-state outbreak of listeriosis. 

 

In September the FDA inspected Jensen Farms, collected samples, and found that 13 of the 39 environmental samples tested positive for Listeria monocytogenes with pulsed-field gel electrophoresis (PFGE) pattern combinations that were indistinguishable from three of the four outbreak strains collected from affected patients. In addition, cantaloupe collected from the firm’s cold storage during the inspection was also confirmed positive for Listeria monocytogenes with PFGE pattern combinations that were indistinguishable from two of the four outbreak strains.

 

As a result of the isolation of outbreak strains of Listeria monocytogenes in the environment of the Jensen Farms cantaloupe packing facility and whole cantaloupes collected from cold storage, and the fact that this is the first documented listeriosis outbreak associated with fresh, whole cantaloupe in the United States, FDA initiated an environmental assessment in conjunction with Colorado state and local officials. FDA, state, and local officials conducted the environmental assessment at Jensen Farms on September 22-23, 2011. The environmental assessment was conducted to gather more information to assist FDA in identifying the factors that potentially contributed to the introduction, growth, or spread of the Listeria monocytogenes strains that contaminated the cantaloupe. 

 

Jensen Farms voluntarily recalled its whole cantaloupes on Sept. 14 in response to the multi-state outbreak of listeriosis.

 

FDA identified the following factors as those that most likely contributed to the introduction, spread, and growth of Listeria monocytogenes in the cantaloupes:

 

Introduction:

Spread:

Growth:

FDA’s findings regarding this particular outbreak highlight the importance for firms to employ good agricultural and management practices in their packing facilities as well as in growing fields. FDA recommends that firms employ good agricultural and management practices recommended for the growing, harvesting, washing, sorting, packing, storage and transporting of fruits and vegetables sold to consumers in an unprocessed or minimally processed raw form. 

FDA has issued a warning letter to Jensen Farms based on environmental and cantaloupe samples collected during the inspection. FDA’s investigation at Jensen Farms is still considered an open investigation.

 

More information on the epidemiologic investigation is available at CDC.