The FDA said Sunday that a sample of Taylor Farms iceberg lettuce it reported testing positive for cyclospora on Saturday was a false positive, leaving investigators without a confirmed positive product test as a multistate outbreak continues.
The agency said its lab experts re-reviewed the sample and concluded the result was a false positive, leaving no confirmed positive product tests
Benjamin Fanjoy / Getty Images
The FDA said Sunday that a sample of Taylor Farms iceberg lettuce it reported testing positive for cyclospora on Saturday was a false positive, leaving investigators without a confirmed positive product test as a multistate outbreak continues.
After re-reviewing the sample results, FDA laboratory experts concluded that the positive reading was erroneous, quoting their determination that the finding "does not represent true amplification and should be considered a false positive." The agency removed information about the sample from its Saturday update and notified Taylor Farms of its conclusion.
Taylor Fresh Foods said Sunday that the FDA apologized. "To be clear, at this moment, FDA has not identified a single positive product test result for Cyclospora," the company said in a statement.
Taylor Farms' voluntary recall of iceberg lettuce grown and processed in central Mexico, which the company initiated last week, stands unaffected by the false positive finding. The FDA said it continues working with Taylor Farms to ensure recalled product has been removed from the market, and that state partners are continuing to collect and analyze product samples.
Rutgers University food science department chair Donald W. Schaffner told NBC News that the recall was justified independent of any laboratory findings, and praised the FDA for having the courage to own up to its mistake. "Unfortunately testing for this organism is difficult," he said. "False positives are always possible."
The FDA's traceback investigation had identified Taylor Farms de Mexico as the supplier of shredded iceberg lettuce served at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, and West Virginia, where sickened customers had eaten. Of those who reported eating at Taco Bell, 1,644 illnesses have been confirmed across the five states, with 94 hospitalizations and no deaths. Taco Bell has said it stopped using lettuce from Taylor Farms de Mexico as of July 17.
The Taco Bell cluster is part of a broader national surge in cyclosporiasis cases. Since May 1, the CDC has counted nearly 7,000 cyclosporiasis cases across the country that are either confirmed or still under investigation, according to NBC News. The FDA and state agencies said they are continuing to collect samples and investigate the source of the contamination.
The FDA advises consumers who purchased recalled Taylor Farms iceberg lettuce to discard it and not consume it. Those experiencing symptoms of cyclosporiasis should contact a health care provider.
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