This photo is not from a field in the suspected in a 2019 E. coli outbreak, but the FDA says it is representative of a field near a slope where cattle graze. ( Courtesy Food and Drug Administration )

A Food and Drug Administration report on three E. coli outbreaks in the fall of 2019 says cattle operations near leafy greens fields is the most likely source of the pathogens.

The agency did not pinpoint the definitive source of the E. coli, indirect transmission of fecal material from nearby grazing areas as the possible source, spread by water run-off, wind, animals, vehicles and irrigation water.

In a summary of the report’s findings, the FDA’s Center for Food Safety and Applied Nutrition said the investigation into the 2019 outbreaks, and results of prior outbreak investigations, said cattle are a persistent source of E. coli strains.

“These key findings reinforce our concern about the possible impacts of nearby and adjacent land use on the safety of leafy green crops and further underscore the importance of implementing appropriate risk-based preventive measures to reduce the potential for contamination of leafy greens,” according to the FDA.

The agency referred to its 2020 Leafy Greens STEC (Shiga toxin-producing E.coli) Action Plan, released in March, which outlines a three-pronged plan to address recurring E. coli outbreaks traced to romaine and other leafy greens.

Those areas are prevention, response and addressing knowledge gaps.

FDA also has pledged to work with the industry, federal partners, academia, state and local agencies and others, according to the action plan.

“Food safety is a shared responsibility that involves food producers, distributors, manufacturers, retailers, and regulators,” according to the FDA’s summary. “FDA is committed to working with these stakeholders to implement this action plan to ensure that America’s food supply remains among the safest in the world.”

FDA recommendations

In the report, the FDA outlined recommendations for the leafy greens industry:

  • Emphasize/redouble efforts around prevention: Assess growing operations to ensure proper prevention measures are used, including Food Safety Modernization Act regulations and good agricultural practices;
  • Adjacent land use: Prevent contamination from uphill adjacent cattle grazing by increasing buffer zones or adding berms or ditches;
  • Agricultural water: Ensure that agricultural water is safe and of adequate sanitary quality for its intended use;
  • Ensure agricultural water treatments are validated, verified, and in accordance with all applicable laws.
  • Improve traceability: increased use of digitized documents to expedite tracebacks and prevent further illnesses; and
  • Packaging: More consistent use of voluntary source labeling on packaging to help retailers/consumers better identify products during an outbreak.

Investigation results

The FDA’s investigation into the fall 2019 outbreaks led to several California farms, according to report.

Key findings include:

  • Each of the three outbreaks was caused by distinctly different strains of E. coli O157.H7, according to whole genome sequencing;
  • Traceback identified a common grower with multiple ranches/fields that supplied romaine to multiple businesses associated with the three outbreaks;
  • Outbreak A’s strain was found in two brands of salad bags with romaine;
  • Outbreak A’s strain was found in a fecal-soil sample taken from a cattle grate less than two miles upslope from a farm with multiple fields tied to the outbreaks; and
  • Other E. coli strains that were not linked to the three outbreaks were found near romaine crops, including two samples from a border area of a farm downhill from cattle grazing land, and two samples from on-farm drainage basins.

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Submitted by micb on Fri, 05/22/2020 - 18:53