On May 25, the FDA published a constituent update notifying the public of released findings from a sampling assignment that tested raw agricultural commodity romaine lettuce at facilities and on farms in the Salinas, California and Yuma, Arizona growing regions for the presence of pathogens linked to foodborne illness outbreaks. The sampling assignment report is available here. The sampling assignment focused on pathogenic Escherichia coli (specifically, Shiga toxin-producing E. coli or STEC) and Salmonella spp. The assignment ran from November 2019 until December 2020, although there was a pause in sampling and testing from March through October 2020 due to the COVID-19 pandemic. No pathogens were detected during the assignment.

The FDA focused on sample collection at farms and facilities that had been identified in traceback investigations as suppliers of romaine lettuce that may have been linked to foodborne illness outbreaks from 2017 to 2019. Summaries of the outbreaks are available here, here, and here. During the assignment, the FDA collected and tested 279 samples for both pathogens. Each sample contained 10 subsamples, each of which consisted of one or more heads or hearts of romaine lettuce and weighed at least 300 grams. The Agency noted that this approach increased the probability of detecting pathogens, if present.

As stated, no pathogens were detected. However, in the constituent update, the FDA mentioned that they intend to continue to monitor the microbiological safety of leafy greens during growing and harvesting seasons. For instance, as previously reported, the FDA announced a new sampling plan to collect approximately 500 samples of romaine lettuce from commercial coolers and cold storage facilities, which hold lettuce from multiple farms in the Yuma region, for STEC and Salmonella as part of the Agency’s ongoing surveillance efforts.