The FDA’s Investigation at Jensen Farms

On September 10, 2011, with Colorado state officials, the FDA conducted an inspection at Jensen Farms and collected multiple samples, both product and environmental, for laboratory testing.  Of the 39 environmental swabs collected from within the Jensen Farms packing facility, 13 were confirmed positive for Listeria monocytogenes with PFGE pattern combinations that were indistinguishable from three of the five outbreak strains.  Of the 13 positive environmental swabs, 12 were collected at the processing line and one was collected from the packing area.  Cantaloupe collected from the firm’s cold storage during the inspection also tested positive for Listeria—in fact, five of the ten samples collected were positive for Listeria—with PFGE pattern combinations that were indistinguishable from two of the five outbreak strains.

After finding evidence of extensive contamination at Jensen Farms, the FDA, again with the assistance of Colorado state officials, conducted an environmental assessment at the facility in an effort to identify the practices and conditions that lead to such widespread contamination.  The results of the assessment, which occurred on September 23 and 24, 2011, were disclosed in a report dated October 19, 2011.  Among other things, the report notes:

a.   Facility Design:  Certain aspects of the packing facility, including the location of a refrigeration unit drain line, allowed for water to pool on the packing facility floor in areas adjacent to packing facility equipment.  Wet environments are known to be potential reservoirs for Listeria monocytogenes and the pooling of water in close proximity to packing equipment, including conveyors, may have extended and spread the pathogen to food contact surfaces.  Samples collected from areas where pooled water had gathered tested positive for an outbreak strain of Listeria monocytogenes.  Therefore, this aspect of facility design is a factor that may have contributed to the introduction, growth, or spread of Listeria monocytogenes.  This pathogen is likely to establish niches and harborages in refrigeration units and other areas where water pools or accumulates.

Further, the packing facility floor where water pooled was directly under the packing facility equipment from which FDA collected environmental samples that tested positive for Listeria monocytogenes with PFGE pattern combinations that were indistinguishable from outbreak strains.  The packing facility floor was constructed in a manner that was not easily cleanable.  Specifically, the trench drain was not accessible for adequate cleaning.  This may have served as a harborage site for Listeria monocytogenes and, therefore, is a factor that may have contributed to the introduction, growth, or spread of the pathogen.

b.   Equipment Design:  FDA evaluated the design of the equipment used in the packing facility to identify factors that may have contributed to the growth or spread of Listeria monocytogenes.  In July 2011, the firm purchased and installed equipment for its packing facility that had been previously used at a firm producing a different raw agricultural commodity.

The design of the packing facility equipment, including equipment used to wash and dry the cantaloupe, did not lend itself to be easily or routinely cleaned and sanitized.  Several areas on both the washing and drying equipment appeared to be un-cleanable, and dirt and product buildup was visible on some areas of the equipment, even after it had been disassembled, cleaned, and sanitized.  Corrosion was also visible on some parts of the equipment.  Further, because the equipment is not easily cleanable and was previously used for handling another raw agricultural commodity with different washing and drying requirements, Listeria monocytogenes could have been introduced as a result of past use of the equipment.

The design of the packing facility equipment, especially that it was not easily amenable to cleaning and sanitizing and that it contained visible product buildup, is a factor that likely contributed to the introduction, growth, or spread of Listeria monocytogenes.  Cantaloupe that is washed, dried, and packed on unsanitary food contact surfaces could be contaminated with Listeria monocytogenes or could collect nutrients for Listeria monocytogenes growth on the cantaloupe rind.

c.   Postharvest Practices:  In addition, free moisture or increased water activity of the cantaloupe rind from postharvest washing procedures may have facilitated Listeria monocytogenes survival and growth.  After harvest, the cantaloupes were placed in cold storage.  The cantaloupes were not pre-cooled to remove field heat before cold storage.  Warm fruit with field heat potentially created conditions that would allow the formation of condensation, which is an environment ideal for Listeria monocytogenes growth.

The combined factors of the availability of nutrients on the cantaloupe rind, increased rind water activity, and lack of pre-cooling before cold storage may have provided ideal conditions for Listeria monocytogenes to grow and out-compete background microflora during cold storage.  Samples of cantaloupe collected from refrigerated cold storage tested positive for Listeria monocytogenes with PFGE pattern combinations that were indistinguishable from two of the four outbreak strains.

See FDA Environmental Assessment Report, Attachment No. 1.

After conducting this environmental assessment, the FDA issued a warning letter to Jensen Farms, indicating that “we may take further action to seize your product(s) and/or enjoin your firm from operating.  Additionally, the receipt of this warning letter and any action taken to correct the violations cited in it do not preclude a subsequent criminal prosecution by the United States Department of Justice.”  See FDA Warning Letter to Jensen Farms, Attachment No. 2.  To date, despite 32 deaths, one miscarriage, and 146 confirmed illnesses nationally, no criminal indictments have issued in this outbreak—yet.

But the FDA did not close its file on this outbreak after issuing its very clear warning.  Officials from the agency also participated in the much-publicized briefings with the House Committee on Energy and Commerce in October and December 2011.  At those meetings, FDA officials cited multiple failures at Jensen Farms, which, according to the Committee Report, “reflected a general lack of awareness of food safety principles.”  Those failures, several of which draw from the FDA’s Environmental Assessment Report, included:

  • Condensation from cooling systems draining directly onto the floor;
  • Poor drainage resulting in water pooling around the food processing equipment;
  • Inappropriate food processing equipment which was difficult to clean (i.e., Listeria found on the felt roller brushes);
  • No antimicrobial solution, such as chlorine, in the water used to wash the cantaloupes; and
  • No equipment to remove field heat from the cantaloupes before they were placed into cold storage.

In particular, the FDA heavily criticized the decision not to chlorinate the water used to wash cantaloupes, despite the fact that the wash was not re-circulated, as well as the use of improper processing equipment in the packing house.  As is discussed below, both of these factors not only contributed to the cause of the outbreak, but were the subject of discussion and recommendation by Primus Labs and its agent Bio Food Safety during the latter’s 2011 audit at Jensen Farms.

In short, the conditions, personnel, and facility in general at Jensen Farms in summer 2011 did not just fall well-short of good manufacturing practices and industry standard, they violated FDA guidance on the safe production of cantaloupes.  Some even violated basic, not to mention legal, standards of human decency.[1]  In fact, this is specifically the opinion held by FDA officials who spoke with the Committee in October and December:  “FDA officials stated that the outbreak could have likely been prevented if Jensen Farms had maintained its facilities in accordance with existing FDA guidance.”’

See Energy and Commerce Committee Report, Attachment No. 3.

[1]           As was widely reported in the press, the US Department of Labor assessed a civil penalty on Jensen Farms for “failing to provide migrant worker housing that meets the safety and health requirements of the Migrant and Seasonal Agricultural Worker Protection Act.”  The “Gateway Motel” in Holly, Colorado, owned by the Jensen brothers, had been “renting” rooms to Jensen Farms workers that were overcrowded, lacked functional windows, lacked any laundry facilities, lacked smoke detectors, and had numerous other unsanitary conditions.  The Department of Justice rejected the Jensen brothers argument that they were “innkeepers” and thus exempt from the reach of the Act.  Chad Frasier, the Wage and Hour Division’s district director in Denver stated that the Jensen brothers’ actions in housing their workers in such deplorable conditions was both “inhumane” and “illegal.”