FDA has reported new results from its investigation of the multi-state outbreak of E. coli O157:H7 linked to romaine lettuce: it has traced the source of the contamination to at least one specific farm. Based on these and other new findings, the agency has updated its recommendations for the romaine lettuce industry and consumers.
FDA identified a positive sample result for the outbreak strain in the sediment of a local irrigation reservoir used by a single farm owned and operated by Adam Bros. Farms in Santa Barbara County. The agency will be sending investigators back to this farm for further sampling.
However, a statement from Statement from FDA Commissioner Scott Gottlieb, M.D. and FDA Deputy Commissioner Frank Yiannas stated, “It’s important to note that although this is an important piece of information, the finding on this farm doesn’t explain all illnesses, and our traceback investigation will continue as we narrow down what commonalities this farm may have with other farms that are part of our investigation.”
While the analysis of the strain found in the people who got ill and the sediment in one of this farm’s water sources is a genetic match, FDA’s traceback work suggests that additional romaine lettuce shipped from other farms could also likely be implicated in the outbreak. Therefore, the water from the reservoir on this single farm doesn’t fully explain what the common source of the contamination, the statement added. FDA is continuing to investigate what commonalities there could be from multiple farms in the region that could explain this finding in the water, and potentially the ultimate source of the outbreak.
The positive sample from the single farm was collected by the FDA and analyzed by the CDC and determined to match the outbreak strain of E. coli through whole genome sequencing (WGS) analysis. Adams Bros. Farms is cooperating with the FDA in this outbreak investigation and hasn’t shipped any romaine lettuce since Nov. 20. The company has committed to recalling products that may have come into contact with the agricultural water reservoir, and FDA is working with the farm to determine how the contamination occurred and whether corrective actions are needed before their next growing season.
As of Dec. 13, the investigation yielded records from five restaurants in four states that have identified 11 distributors, nine growers, and eight farms as potential sources of contaminated romaine lettuce. Currently, no single establishment is common across the investigated supply chains. “This indicates that although we have identified a positive sample from one farm to date, the outbreak may not be explained by a single farm, grower, harvester, or distributor,” the statement said.
While this new information does not fully explain the outbreak, it does allow FDA to revise its recommendations for consumers slightly. Given the identification of the outbreak pathogen on the farm in Santa Barbara county, the farms identified in the traceback, and the fact that the lettuce on the market at the peak of the outbreak should be beyond shelf-life the agency feels there is no longer a reason for consumers to avoid romaine lettuce from San Luis Obispo, Santa Cruz and Ventura Counties, in California, provided it was harvested after Nov. 23. If consumers, retailers, and food service facilities are unable to confirm that romaine lettuce products are from unaffected sources, FDA urges that these products not be purchased, or if the products have already purchased, they should be discarded or returned to the place of purchase.
Romaine lettuce that was harvested outside of Monterey, San Benito, and Santa Barbara Counties in California after Nov. 23 doesn’t appear to be related to the current outbreak. Hydroponically and greenhouse-grown romaine also doesn’t appear to be related to the current outbreak. There’s no reason for consumers or retailers to avoid using romaine harvested from these sources.
As of Dec. 13, the outbreak had resulted in 59 people becoming ill in 15 states, with the last reported illness onset date being Nov. 16. FDA, CDC, and its partners are also coordinating the investigation with Canadian health and food safety authorities who are also looking into a related outbreak.