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E Coli bacteria on US grown Spinach update: |
UC and federal scientists have proposed ramping up a long-planned study of E. coli in Monterey County to include areas of San Benito County where spinach implicated in the September 2006 E. coli outbreak might have been grown.
For the last 5 years, UC researchers conducting on-farm tests of lettuce, soil, irrigation water and runoff in the Salinas Valley did not detect any of the virulent E. coli O157:H7 bacteria that caused the September 2006 spinach outbreak.
UC Davis postharvest specialist Trevor Suslow and Monterey County farm advisor Steve Koike conducted hundreds of tests. “We have demonstrated that populations of nonpathogenic E. coli on lettuce in the majority of fields is very low,” Suslow says. “To this date, we have never encountered detectable levels of viable, pathogenic E. coli using methods of high sensitivity and specificity.”
However, since 1995, more than 15 illness outbreaks have been associated with lettuce or spinach consumption in the United States and Canada — and several have been traced to the Salinas Valley.
“We know that detectable levels of pathogenic E. coli have been found outside the farm, for instance in watersheds and drainage creeks — water sources that are not used for irrigation,” Suslow says. “E. coli O157:H7 clearly occurs in the natural environment, and there are natural events such as wild animal movements or flooding that could introduce these pathogens to farmed land. The challenge is to learn whether and how they may survive, and develop management practices that protect food production areas from contamination.”
In evaluating various E. coli O157:H7 detection methods, the researchers also found that several commercially available rapid-detection testing kits routinely gave “false positive” results. “An incorrect interpretation of results from these end-point tests could cause growers a lot of problems,” Koike says.
The study, funded by the California Lettuce Research Board, has helped the scientists develop baseline microbiological indicator data for irrigation water, soil survival and lettuce, and has led to better understanding of the variability among fields and common crop production practices, Koike says.
source: California Agriculture, University of California, Issue March 2007.©[2007]
Tips for handling produce to keep your family clear of pathogens:
- Buy produce that is refrigerated or on ice.
- Wash all fresh fruit and produce. A brush can be used on tough-skinned items like cucumbers and apples. Drying offers further protection. Be sure to have paper towel or a clean towel on hand.
- Keep worktop surfaces and cutting boards clean. A clean refrigerator is another bonus. The Center for Disease Control advises using chlorine bleach when washing countertops and sink drains (recommended dilution: one teaspoon of bleach in one quart of water).
- Don’t eat raw sprouts, specifically bean, alfalfa, clover and radish sprouts.
For more handing tips see The USDA’s Center for Food Safety and Applied Nutrition www.cfsan.fda.gov/~dms/prodsafe.html ) or Fight BAC! www.fightbac.org .
 
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