000852 Cross Contamination Led to Restaurant E Coli Outbreak

New York - Not all E. coli outbreaks traced to restaurant food is due to undercooked meat, researchers suggest. One study of a 1993 outbreak in the US Northwest shows that cross contamination of meat products and salad items in restaurant kitchens may also lead to E. coli infections in patrons.

Escherichia coli (E. coli) outbreaks occurred in four steak and salad bar restaurants located in Oregon and Washington. The restaurants, all affiliated with the same national chain, served foods purchased ready-to-serve as well as foods prepared on the premises.

Three of the outbreaks occurred in March 1993 and one outbreak occurred in August 1993, involving a total of 39 confirmed cases of E. coli strain 0157:H7 and 54 probable cases. Fifteen individuals were hospitalized, but none developed hemolytic uremic syndrome--a serious complication of E. coli that can lead to kidney failure--and none died, according to a report published in the August 14/28 issue of Archives of Internal Medicine.

The cause of the outbreaks seemed mysterious, the study suggests. “Surprisingly, consumption of beef or other meats was not associated with disease in any of these outbreaks,” writes lead author Dr. Lisa Jackson, an associate professor in the University of Washington's department of epidemiology. Previous E. coli outbreaks in fast food restaurants have been traced to undercooked beef.

All of the foods implicated in the outbreaks were salad bar items, yet no single salad bar item was implicated in all of the outbreaks, the authors comment. Some specific items associated with illness included cantaloupe, mayonnaise-containing foods, lettuce and bulk prepackaged shredded cheese, the investigators note.

“We found that the Seattle (Washington) outbreak was caused by multiple strains of E. coli O157, which is unusual,” Jackson said. “We believe that we found multiple strains because cross contamination occurred from several cuts of meat,” she stated.

At least 2 of the restaurants may have been guilty of possible cross contamination of foods--”raw meat was being processed and stored in close proximity to raw vegetables and other food products,” write Jackson and her colleagues. However, the authors did not find any direct evidence of improper food handling that could have caused the outbreak.

Yet, the restaurant chain “may have been exceptionally susceptible to cross- contamination because on-site meat cutting and large, diverse salad bar operations were combined,” the authors speculate.

“To prevent these types of outbreaks, care must be taken to minimize the possibility of cross-contamination from beef to other food products,” Jackson stated. In addition, the authors stress the “need for meticulous food handling at all stages of preparation in commercial and home settings.”

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