Top Takeaways from FDA Report on Recurring E. Coli Outbreaks

Ensuring that outbreak response activities are conducted as quickly and thoroughly as possible is essential for preventing illnesses, Dr. Gorny says. In addition, it is critical that FDA and stakeholders share lessons learned to inform future prevention efforts.

“Much of the 2021 focus is on improving information sharing between FDA and the industry and improving the rapidity and accuracy of traceback investigations,” Dr. Miller says. “Sharing learnings from past outbreaks can help the FDA and industry better understand potential sources of contamination. Traceback investigations have demonstrated their usefulness in helping determine the cause of outbreaks and point investigators to suspect growing fields to narrow the scope of field investigations and sampling. Improving traceability can also limit the impact and scope of consumer advisories when the next outbreak occurs if the source of an outbreak can be quickly identified.”

While FDA and stakeholders have greatly expanded what is known about leafy greens safety, knowledge gaps still exist, which can be explored in new ways through the use of emerging technologies, Dr. Gorny says. Addressing these knowledge gaps is critical to advancing future prevention activities.

It’s also important to recognize that these are not siloed areas of focus, but rather numerous points of intersection and mutual reinforcement, Dr. Gorny adds.

Each of these three approaches acknowledges a current lack of data or consensus in a particular area. “By collecting more data, FDA hopes to create a more objective assessment of contributing risk factors and preventive measures for leafy greens grown in the Yuma and Salinas regions,” Dr. Miller says.

Outlook

FDA and the leafy greens industry have been working to reduce E. coli contamination in leafy greens since 2006. “A lot of progress has been made and, while the risk is less today than it was in 2006, the ongoing outbreaks show that risks still exist,” says David Acheson, MD, CEO, and president of The Acheson Group.

Obviously, the problem has not been resolved despite the California Leafy Greens Marketing Agreement, a program implemented in 2007 to ensure safe leafy greens and a much greater use of testing than in the past, Dr. Acheson says. “Part of the problem links back to gaining a better understanding of the root cause, for example, the movement of E. coli in dust and driven by the wind—which is hard to control,” he says.

Dr. Acheson says situations still exist in which growers are not fully leveraging what is known around risk: Some still grow lettuce at the bottom of a hill on which cattle are grazing. While there are many more controls in place today, along with regulatory requirements in the form of the FSMA Final Rule on Produce Safety, the risks remain and the ultimate controls are elusive. “As long as both live animals and leafy greens are raised in the same broader environment, this problem is not likely to totally go away,” he says.

Mitigating the Issue

In order to resolve the issue of E. coli contaminating leafy greens, Dr. Miller says it’s important to understand how STEC from the environment makes its way onto leafy greens. “Monitoring and treating irrigation water is common sense and an achievable control compared to controlling by windborne contamination,” he says. “Seasonal climate patterns may contribute to windborne contamination in the Salinas Valley; more research is needed in this area to understand the role that weather, climate, and cattle proximity play in field-level contamination.”

A root cause analysis will seek to eliminate the hazard at its source, as cattle are a known and well-documented reservoir for STEC, Dr. Miller says. Cattle vaccines against E. coli O157:H7 are commercially available, although their uptake has been limited. Cattle may not be the only source of environmental STEC where lettuce is grown, although FDA investigations in 2019 and 2020 identified the outbreak strain in cattle feces surrounding growing fields identified in traceback investigations.