After four outbreaks in less than two years where likely contaminated romaine lettuce contained deadly E. coli O157: H7, the Food and Drug Administration has decided to turn to microbial testing for clues for the next year to try to figure out what’s happening.

Sampling and testing food is FDA’s business.

Earlier this year, the agency announced microbiological testing for frozen berries. Frozen raspberries, blackberries, and strawberries were implicated “in recent decades” for viral infection outbreaks.

But not since 2012 have raw agricultural commodities been subject to comprehensive sampling and testing. That’s when USDA’s Microbiological Data Program (MDP) ended.

The FDA reports it is now “conducting a small, focused assignment to collect samples of the raw agricultural commodity (RAC) romaine lettuce to test for Salmonella app and pathogenic Escherichia coli. . .”

The year-long testing program is set to run through November 2020. Testing for Shiga Toxin-producing E. coli or STECS includes the microbial hazards that are associated with romaine lettuce consumption.

FDA will collect raw lettuce that is trimmed or washed in its natural form before processing. No fresh-cut processed romaine will be collected or analyzed. The agency announcement explains it this way:

“Sampling of RAC romaine lettuce before it is commingled during fresh-cut processing or before preparation at point of service where it may be commingled with other produce enables FDA to quickly trace lettuce to the point of origin when samples test positive for the presence of a human pathogen.”

FDA’s question-answer information  included:

Where will the samples be collected?
The agency plans to prioritize sampling at FDA registered facilities and farms identified by traceback from 2017 to present amid foodborne illness outbreaks for which romaine lettuce was confirmed or suspected to be the food vehicle. This domestic sampling assignment may include wholesalers, foodservice distribution centers, and commercial cooling and cold storage facilities, including on-farm holding facilities. Samples will only be collected after harvest and not from growing fields.

When will FDA collect samples?
The agency plans to collect samples throughout the year from November 2019 to November 2020,  with increased frequency in March-April and October-November, the transition periods for the California Central Coast and Central Valley to/from the Imperial/Yuma Valley growing regions, when foodborne illness outbreaks associated with romaine lettuce consumption have most frequently occurred.  Samples will be collected Mondays through Thursdays, to allow time for the shipment and help forestall any delay with respect to the testing.

How many samples will FDA collect?
The FDA plans to collect 270 samples in all. Each sample will consist of 10 subsamples, with each subsample weighing a minimum of 300 grams. This approach –- the collection and testing of samples composed of multiple subsamples –- is more reflective of actual conditions, and it increases the odds of finding pathogens if present, given that microbial hazards may not be uniformly present. Accordingly, if one subsample tests positive for a target pathogen, the FDA will regard the entire sample as positive for the organism.

How will the samples be collected?
Consistent with the FDA’s standard approach, agency field staff will collect all samples aseptically to prevent contamination during the collection process. The FDA’s aseptic sampling methods, which entail the use of sterile implements and containers, and prescribed collection procedures, are published in the agency’s Investigations Operations Manual (Chapter 4; Sub- Chapter 4.3).

Samples will be held and shipped at refrigerated temperatures. Agency field staff will ship samples in insulated transport containers with cooling media. Given that romaine lettuce is highly perishable, all shipments will occur overnight via a next-day courier service.

Per the Investigations Operations Manual (Chapter 4; Sub-Chapter 4.4), FDA field staff will collect information such as the name and address of the product manufacturer and/or distributor, the collection site, photographs of the product label, the food identification code (lot codes), and supply chain information.

What test methods will the FDA use?
In testing for pathogenic E. coli, FDA analysts will follow the methods in Chapter 4A of the FDA’s Bacteriological Analytical Manual (BAM). In testing for Salmonella spp., FDA analysts will follow the methods in BAM Chapter 5.

How soon after sample collection will the FDA provide the test results?
The FDA understands that some firms may opt to hold product pending notification of test results. In all cases, the FDA will notify the firm of the test results as soon as possible following the completion of the testing.
Notification of test results generally will occur within three to four days following sample collection (i.e., for negative results and cannot-rule-out initial findings). If the agency detects a cannot-rule-out initial finding, notification of final results may take up to an additional seven days.

The FDA also will perform whole genome sequencing on the pathogens it detects and then uploads the data to the public sequence repository, which generally takes up to an additional week. The agency routinely notifies firms of the results of the bioinformatic analysis of the sequence data, which may include communicating linkages to clinical illness or other food or environmental isolates.

Follow-up and enforcement
If the FDA detects Salmonella spp. or pathogenic E. coli in a sample, the agency will notify the firm of the findings and work with the firm to take appropriate action to protect the public health. The FDA encourages voluntary corrective action and, in all cases, seeks to employ an approach of “educate before and while we regulate.”

For samples traced back to a farm in a state that holds a grant with the FDA under the State Produce Implementation Cooperative Agreement Program, the FDA will work with the state to coordinate any necessary follow-up at the farm. The agency may consider multiple compliance and enforcement actions based on the available evidence and the adequacy of the firm’s response to prevent future contamination. Enforcement activities include actions to correct and prevent violations and to remove violative food from the market, as appropriate.

MDP
From 2002-2011, the the USDA’s Microbiological Data Program (MDP) conducted tests in 42 states on 120,887 samples of fruits and vegetables, including cantaloupe, celery, green onions, hot peppers, leaf lettuce, romaine lettuce, bagged lettuce, parsley, peanut butter, spinach, bagged spinach, alfalfa sprouts and tomatoes.

MDP testing was conducted by laboratories at Land Grant universities around the country with funding from Congress that was administered by USDA.   Congress terminated the program in 2012, the year after the Food Safety Modernization Act was signed into law. No similar testing existed when the romaine outbreaks began in 2017 and 2018.

Romaine Outbreaks
An E. coli O157: H7 outbreak in late 2017 was linked to simply to leafy greens in the U.S, while it was “likely romaine” in Canada, according to investigators.

Two 2018 E.coli outbreaks were linked to romaine, as was a fourth event that FDA covered up for six weeks this fall. The four E. coli outbreaks infected a total of 320 people.  The outbreaks were notable for their high hospitalization rates. Five outbreak patients died.

The romaine outbreaks were traced to growing regions, but not the actual farms where they were grown.