A novel approach to enhance food safety: industry-academia-government partnership for applied research.

An independent collaborative approach was developed for stimulating research on high-priority food safety issues. The Fresh Express Produce Safety Research Initiative was launched in 2007 with $2 million in unrestricted funds from industry and independent direction and oversight from a scientific advisory panel consisting of nationally recognized food safety experts from academia and government agencies. The program had two main objectives: (i) to fund rigorous, innovative, and multidisciplinary research addressing the safety of lettuce, spinach, and other leafy greens and (ii) to share research findings as widely and quickly as possible to support the development of advanced safeguards within the fresh-cut produce industry. Sixty-five proposals were submitted in response to a publicly announced request for proposals and were competitively evaluated. Nine research projects were funded to examine underlying factors involved in Escherichia coli O157:H7 contamination of lettuce, spinach, and other leafy greens and potential strategies for preventing the spread of foodborne pathogens. Results of the studies, published in the Journal of Food Protection, help to identify promising directions for future research into potential sources and entry points of contamination and specific factors associated with harvesting, processing, transporting, and storing produce that allow contaminants to persist and proliferate. The program provides a model for leveraging the strengths of industry, academia, and government to address high-priority issues quickly and directly through applied research. This model can be productively extended to other pathogens and other leafy and nonleafy produce.

A multistate outbreak of Escherichia coli O157:H7 infection linked to consumption of beef tacos at a fast-food restaurant chain.

We investigated a multistate outbreak of Escherichia coli O157:H7 infections. Isolates from 13 case patients from California, Nevada, and Arizona were matched by pulsed-field gel electrophoresis subtyping. Five case patients (38%) were hospitalized, and 3 (23%) developed hemolytic uremic syndrome; none died. The median age was 12 years (range, 2-75 years), and 10 (77%) were female. Case-control studies found an association between illness and eating beef tacos at a national Mexican-style fast-food restaurant chain (88% of cases versus 38% of controls; matched OR, undefined; 95% confidence interval, 1.49 to infinity; P=.009). A trace-back investigation implicated an upstream supplier of beef, but a farm investigation was not possible. This outbreak illustrates the value of employing hospital laboratory-based surveillance to detect local clusters of infections and the effectiveness of using molecular subtyping to identify geographically dispersed outbreaks. The outbreak investigation also highlights the need for a more efficient tracking system for food products.

Industry practices and compliance with U.S. Food and Drug Administration guidelines among California sprout firms.

Since 1995, raw vegetable sprouts have been implicated as the vehicle of infection in 15 foodborne outbreaks involving Salmonella and 2 foodborne outbreaks involving Escherichia coli O157:H7. To reduce the numbers of sprout-related outbreaks, the U.S. Food and Drug Administration (FDA) published Guidance for Industry: Reducing Microbial Food Safety Hazards for Sprouting Seeds in 1999. Between October 2000 and April 2001, 61.5% (16 of 26) of the known commercial sprout firms in California were enrolled in a survey to evaluate the industry practices of California sprouting operations and to determine compliance with FDA guidelines. A standardized questionnaire was used to collect data on firm demographics and seed disinfection practices. Additionally, free chlorine levels in seed disinfection solutions were measured, and 48-h spent irrigation water samples were collected from each firm. The irrigation water was screened for Salmonella and E. coli O157:H7 with FDA-recommended test kits. Free chlorine levels in the treatment solutions ranged from 50 to 35,000 mg/liter (ppm), with a median of 14,000 mg/liter (ppm). Free chlorine levels were higher for firms producing alfalfa sprouts than for those producing only mung bean or soybean sprouts (P=0.03). Levels of free chlorine tended to be higher for firms using a calcium hypochlorite treatment solution than for firms using a sodium hypochlorite treatment solution (P=0.067). All 32 irrigation water samples screened for Salmonella tested negative. Of the irrigation water samples tested for E. coil O157:H7, 75% (24 of 32) tested negative, and 25% (8 of 32) tested presumptive positive. The eight presumptive positive samples were found to be negative after further testing. These results indicate that producers of alfalfa sprouts are generally achieving the FDA-recommended calcium hypochlorite level of 20,000 mg/liter (ppm), whereas mung bean sprout producers are not.

Escherichia coli O157:H7 in feral swine near spinach fields and cattle, central California coast.

We investigated involvement of feral swine in contamination of agricultural fields and surface waterways with Escherichia coli O157:H7 after a nationwide outbreak traced to bagged spinach from California. Isolates from feral swine, cattle, surface water, sediment, and soil at 1 ranch were matched to the outbreak strain.

Alfalfa seed decontamination in a Salmonella outbreak.

Based on in vitro data, the U.S. Food and Drug Administration recommends chemical disinfection of raw sprout seeds to reduce enteric pathogens contaminating the seed coats. However, little is known about the effectiveness of decontamination at preventing human disease. In 1999, an outbreak of Salmonella enterica serotype Mbandaka occurred in Oregon, Washington, Idaho, and California. Based on epidemiologic and pulsed-field gel electrophoresis evidence from 87 confirmed cases, the outbreak was linked to contaminated alfalfa seeds grown in California's Imperial Valley. Trace-back and trace-forward investigations identified a single lot of seeds used by five sprout growers during the outbreak period. Cases of salmonellosis were linked with two sprout growers who had not employed chemical disinfection; no cases were linked to three sprout growers who used disinfection. This natural experiment provides empiric evidence that chemical disinfection can reduce the human risk for disease posed by contaminated seed sprouts.

Multistate shigellosis outbreak and commercially prepared food, United States.

In 2000, shigellosis traced to a commercially prepared dip developed in 406 persons nationwide. An ill employee may have inadvertently contaminated processing equipment. This outbreak demonstrates the vulnerability of the food supply and how infectious organisms can rapidly disseminate through point-source contamination of a widely distributed food item.