Sprouts not always a "health" food - Food Safety - Brief Article

Nutrition Research Newsletter, Oct, 2001

Vegetable sprouts have long been used medicinally in Asia and are now commonly consumed by health-conscious Americans. While the nutritional makeup of sprouts is very "healthy", they can be a dangerous food product. Raw sprouts have been associated with salmonellosis outbreaks in the United States, Canada, and Europe and of Shiga toxin-producing Escherichia coli O157 infections in the US and Japan. The US Food and Drug Administration recently issued consumer advisories for spouts and recommend that sprout producers decontaminate seeds and obtain microbiologic testing of in-line or finished sprouts.

From 1996 through 1998, investigators evaluated five multi-county incidences of salmonellosis outbreaks and one outbreak of E. coli O157 infection in California that were associated with alfalfa or clover sprouts. The study was performed in a case-control design. California's Microbial Diseases Laboratory (MDL) identified each outbreak studied. Traceback investigations of sprouts eaten by patients and seeds used to produce the sprouts, including environmental investigations of implicated sprout growers and seed growers, were conducted. In order to identify a food associated with illness, matched case-control studies were conducted. Case-patients were questioned regarding where they had purchased or consumed sprouts. Investigators then visited retailers and reviewed invoices to identify sprout growers and visited implicated sprout growers. For each sprout grower, invoices for seed purchases and records for sprout manufacturing processes were reviewed in order to determine possible sources of contamination.

Five sprout-associated outbreaks of salmonellosis and one outbreak of infection with nonmotile Shiga toxin-producing E. coli O157 occurred in the two-year investigation period. Six hundred patients had culture-confirmed disease. Unfortunately, two patients died due to contamination. Researchers estimate that these outbreaks caused 22,800 cases of gastrointestinal illness or urinary tract infection. Three sprout growers were implicated as culprits of the outbreaks, and each grower was associated with two outbreaks. Outbreak strains of Salmonella were isolated from sprouts supplied by two sprout growers and from seeds used by the third sprout grower.

As they are currently produced, sprouts are a potentially hazardous food item. Seeds contaminated before sprouting have no way of being sterilized of pathogens. This research makes it quite clear that both seed and sprout growers need to implement measures to decrease potentially fatal contamination. Populations at high risk for developing complications from salmonellosis or E. coli O157, including the immunocompromised, elderly, and children, should avoid consuming sprouts.

J. Mohle-Boetani, J. Farrar, S. Benson Werner, et al. Escherichia coli O157 and Salmonella injections associated with sprouts in California, 1996-1998. Annals of Internal Medicine; 135:239-247 (August 2001) [Correspondence: Janet Mohle-Boetani, MD, MPH, Disease Investigations and Surveillance Branch, Division of Communicable Diseases Control, 2151 Berkeley Way, Room 708, Berkeley, CA 94704. E-mail: jmohlebo@dhs.ca.gov].