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  1. Sampling to Protect the Food Supply

Microbiological Surveillance Sampling

Sampling Main Page

Testing to Support Prevention Under the FDA Food Safety Modernization Act

As part of the FDA’s risk-based and preventive approach to food safety, which is at the core of the FDA Food Safety Modernization Act, the agency began developing a new, more robust approach to deploying its sampling resources in 2014. As the agency moves forward with this approach, it will continue to refine procedures based on lessons learned. The goals of the surveillance sampling are to keep contaminated products from reaching consumers and to facilitate a greater understanding of hazards.

The FDA will publish information regarding test results on the web, including total number of samples collected/tested, and collection date, sample type, and pathogen detected for positive samples.

The Sampling Approach

Under the new sampling approach, the FDA collects a large number of samples of targeted foods over a relatively short period—about 18 months—to ensure that enough data are available to inform decisions. This approach seeks to help the FDA determine if there are common factors among positive findings, such as origin, variety or season. The FDA’s past approach to microbiological surveillance sampling has been to collect a relatively small number of samples of many different commodities over many years.

The sampling design for each food represents what U.S. consumers are likely to find in the marketplace. Accordingly, the agency has considered the volume of the target food that is imported and produced domestically and the number of states/countries that produce the target food.

Commodities Sampled

During the first year of this new effort, the FDA focused on sprouts, whole fresh avocados, and raw milk cheese (aged 60 days). The FDA collected more than 800 samples of each commodity and tested them for Salmonella, Listeria monocytogenes and E. coli O157:H7. For fiscal year 2016, the FDA sampled and tested cucumbers and hot peppers for Salmonella and E. coli O157:H7, taking 1,600 samples of each commodity. The agency also tested hot peppers for Shiga toxin producing E. coli. Beginning with fiscal year 2018, the FDA is sampling fresh herbs, specifically basil, parsley, and cilantro, to test for Salmonella, Shiga toxin producing E. coli, and during the summer months, Cyclospora cayetanensis. Also beginning with fiscal year 2018, the agency is sampling processed avocado and guacamole to test for Salmonella and Listeria monocytogenes.

The FDA will conduct whole genomic sequence testing on any samples that test positive. In the future, the number of samples collected of a targeted commodity may vary, depending on the question(s) the FDA intends to answer.

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Using the Data

The FDA will evaluate the data or results generated throughout the sample collection period and use the data to inform the agency’s short and longer term decision making. By developing these data sets, the FDA seeks to identify potential vulnerabilities and ways to enhance the food safety system.

Depending on the results, the FDA may react or take certain steps, such as:

  • Decreasing sampling, if few positive samples are obtained;
  • Implementing more targeted sampling if trends are identified; for example, if positive samples come from a specific geographic region, a specific facility, or during a particular season;
  • Follow-up inspections;
  • Working with state or international regulatory partners to take corrective actions and implement preventive controls;
  • Developing new or enhanced industry guidance; and
  • Conducting outreach and information sharing to better protect consumers.


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