As part of its efforts to prioritize the safety of leafy greens, the FDA released the results of a sampling assignment involving testing romaine lettuce from commercial coolers in Yuma County, Arizona. Earlier this year the agency announced that it would be collecting samples of romaine lettuce as part of ongoing surveillance following the spring 2018 multistate outbreak of E.coli O157:H7.

The lettuce was tested for Shiga toxin-producing Escherichia coli (STEC), specifically enterohemorrhagic Escherichia coli (EHEC), and Salmonella spp. The FDA collected 504 romaine samples, and an independent lab conducted the testing.

E.coli O130:H11 was found in one sample, and as a result, the FDA conducted an investigation at the farm to find potential sources and routes of contamination—samples of soil, water, sediment and animal fecal material were taken, and the agency also looked at farm equipment and other surfaces. Out of 24 samples, just one came back positive for STEC, and this sample was taken from the outer leaves of the lettuce. It was determined that the strain was low risk to human health, and FDA did not find that this strain was linked to any past known foodborne illness outbreaks.

“The agency’s goal in conducting this assignment was to determine whether the target pathogens and specific strains may be present in romaine lettuce from the Yuma agricultural region, to help prevent foodborne illness when possible,” FDA stated in a constituent update. “If product that tested positive for EHEC or Salmonella was found, the Agency planned to work with industry and state regulatory partners to identify the cause (e.g., farm follow-up investigation) to inform future regulatory and/or research efforts and to develop strategies that could help preventive additional outbreaks.”