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  1. Sampling to Protect the Food Supply

Microbiological Surveillance Sampling: FY21 Collection and Testing of Romaine Lettuce from Commercial Coolers in Yuma County, AZ

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Introduction

The FDA is conducting an assignment to collect romaine lettuce samples from commercial cooling operations in Yuma County, Arizona during the current harvest season to test for microbial hazards repeatedly linked to foodborne illnesses associated with the leafy vegetable.

The agency began this sampling assignment in February, 2021, and plans to continue its collection and testing into April, 2021, through to the end of the harvest season in the Yuma growing region. All samples are being tested for Salmonella spp., Escherichia coli O157:H7, and other Shiga toxin-producing E. coli (STEC).

The FDA has conducted ongoing surveillance of romaine lettuce from the Yuma County agricultural region following the spring 2018 multistate E. coli O157:H7 outbreak of foodborne illness linked to romaine lettuce from the area. This assignment also is part of a larger effort by the FDA, known as its Leafy Greens STEC Action Plan, to help ensure the microbiological safety of leafy vegetables.

Yuma and Romaine Lettuce

Yuma is known as the nation’s “winter salad bowl” because most of the leafy greens and other vegetables eaten by U.S. consumers in the winter and early spring, including romaine lettuce, are grown in the region. California’s Imperial Valley growing region also produces a large portion of the leafy greens eaten in the U.S. during the same period.

Romaine lettuce is grown low to the ground and thus is susceptible to contamination from irrigation water splashing off the soil. Typically planted in rows, romaine lettuce grows in a tall head of sturdy leaves with a firm rib at the center of the shoot. The crop may be harvested by machine or by hand. Romaine lettuce is typically eaten without having undergone a ‘kill step,’ such as cooking, to reduce or eliminate bacteria.


Questions and Answers

The FDA plans to collect 500 samples of romaine lettuce for this assignment. Each sample will consist of 10 subsamples, and each subsample will be made up of at least 300 grams of romaine lettuce (whole heads, hearts or individual leaves).

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