Food Protection Connection: E. Coli in Spinach: Anatomy of an Outbreak

(reprinted from Dietary Manager, November/December 2006)

Each Food Protection Connection column is approved for 1 CPE hour (level 1) for RDs and DTRs.

As of October 2, 2006, the Centers for Disease Control (CDC) reported 187 cases of foodborne illness affecting more than half the states in the nation, including 29 cases of hemolytic uremic syndrome (a form of kidney failure), 95 hospitalizations (more than half of all cases), and two deaths—all attributed to contamination of fresh, bagged spinach with E. coli O157:H7 bacteria. A related case was also reported in Canada.

According to the CDC, among all those ill, 29 percent of the children developed hemolytic uremic syndrome, as did 7 percent of the adult population ages 18 to 59, and 14 percent of people 60 or older. The two deaths represent the extremes of the age spectrum—one two-year old child, and an elderly woman, according to the CDC analysis.

The outbreak commanded almost daily news coverage, and triggered one of the most brisk discussion threads ever in the Dietary Managers Association Member Community, the site of 82 postings among dietary managers discussing the situation and how to respond.

Consumer Advisory and Recalls

Government authorities, including those in various state health departments, began investigating links to bagged spinach. In a number of cases, officials tested the particular strain of E. coli bacteria in a package of bagged spinach, and gradually verified that it was the same strain found among a number of victims through DNA fingerprinting technology. This technology identifies bacteria specifically, much as a fingerprint can identify a person. DNA fingerprint matches were the first major clues linking spinach to the outbreak.

Based on initial findings, the FDA issued an advisory warning consumers throughout the country not to eat any bagged spinach products. Frozen and canned spinach were not affected by the advisory, because these products receive processing treatment that would destroy bacteria. FDA officials also noted that washing spinach would not be an effective step in making it safe, because bacteria could get inside the leaves.

By mid-September, the FDA announced that Natural Selection Foods, LLC, of San Juan Bautista, CA had initiated a voluntary recall of its fresh, bagged spinach products. In turn, this company was supplying spinach to many other companies. According to the FDA (9/17/06), “Natural Selection Foods, LLC brands include: Natural Selection Foods, Pride of San Juan, Earthbound Farm, Bellissima, Dole, Rave Spinach, Emeril, Sysco, O Organic, Fresh Point, River Ranch, Superior, Nature’s Basket, Pro-Mark, Compliments, Trader Joe’s, Ready Pac, Jansal Valley, Cheney Brothers, D’Arrigo Brothers, Green Harvest, Mann, Mills Family Farm, Premium Fresh, Snoboy, The Farmer’s Market, Tanimura & Antle, President’s Choice, Cross Valley, and Riverside Farms.” Initially, packages affected were those with Best if Used by dates of August 17, 2006 through October 1, 2006, according to the FDA. Details on brand names and product date ranges were updated several times.

Looking for Answers

By late September, FDA officials confirmed the suspect spinach was grown in three California counties: Monterey, San Benito, and Santa Clara. However, the cause of contamination had not been pinpointed. As of this writing, investigations are addressing both the growing fields and processing plants. A statement from the FDA (9/29/06) noted “continued inspections and sample collection in facilities, the environment, and water, as well as studies of animal management, water use and the environment.” The CEO of Natural Selection Foods, Charles Sweat, pointed out to CNN (9/28/06), “Tracing the tainted greens back to the individual fields is difficult because spinach from different growers is mixed together before being packaged.” As of this writing, reasons for the contamination are limited to speculation. It will take time for details to unfold.

From a broader perspective, the FDA observed that there has been “a long history of E. coli 0157:H7 outbreaks involving leafy greens from the central California region.” In a statement issued 9/29/06, the FDA said, “After discussions with industry, FDA and the State of California, as part of a longer term strategy, now expect industry to develop a plan to minimize the risk of another outbreak due to E. coli O157:H7 in all leafy greens, including lettuce.”

The FDA had already developed the Lettuce Safety Initiative in response to recurring outbreaks of E. coli O157: H7 in lettuce. The objectives of the initiative are to examine and improve industry practices, alert consumers to possible problems, and consider regulatory action, if warranted. As the spinach situation began unfolding, the FDA announced that it would seek to include spinach in this initiative.

Lessons for Safety

As investigations continue, both consumers and foodservice professionals recognize that the threat of foodborne illness stemming from contaminated produce is real and present...and could occur again. As soon as the FDA issued its advisory, dietary managers began removing fresh spinach from their menus and their kitchens. Beyond following the FDA advisory, many foodservice professionals are seeking ways to minimize future risks associated with fresh, leafy greens. Some advice from the FDA so far includes:

• Store bagged leafy greens under refrigeration (at or below 41ºF).
• Minimize handling of leafy greens to avoid potential cross contamination.

As more information about the recent outbreak emerges, we can expect more advice for the industry, too. Most likely, advice will follow the entire farm-to-fork chain. As of this writing, officials are not able to say when fresh, bagged spinach will again become widely available. They will want to verify safety first. To obtain the latest news on the investigation, check the CDC and FDA “update” Web pages listed below.

E. Coli Overview

E. coli bacteria live in the intestines of animals and humans, and there are many strains. The E. coli O157:H7 strain causes serious illness, both through infection and by producing a toxin (poison) in the body of an infected person. While we often associate the bacteria with ground beef, it has also caused foodborne illness outbreaks through contamination of dairy products, unpasteurized fruit juices, raw seed sprouts, lettuce, and other fresh produce. According to the FDA, “E. coli O157:H7 causes diarrhea, often with bloody stools.

Although most healthy adults can recover completely within a week, some people can develop a form of kidney failure called hemolytic uremic syndrome, which is most likely to occur in young children and the elderly. The condition can lead to serious kidney damage and even death.”

By Sue Grossbauer