According to the Final Reports issued by the State on October 6 and 9, 2000, the outbreak was first noted on July 24 when staff at Children’s Hospital notified the City of Milwaukee Health Department regarding a cluster of E. coli O157:H7 cases. Eventually, sixty-four confirmed cases were discovered – 62 linked to the Layton Sizzler and two linked to the Mayfair Sizzler. Dozens of these individuals were hospitalized; four developed HUS and one of those died. In addition to the confirmed cases, the State noted that there were reports of 551 probable cases, and another 122 possible cases.
Notably, sixty-two of the laboratory-confirmed cases were found to be genetically indistinguishable – proving that all of the cases had a common source. Moreover, an identical strain of the E. coli O157:H7 was isolated from samples of raw chunky taco meat and sirloin tri-tips found at the Layton restaurant. This meat was manufactured by the Excel Corporation, and then remanufactured the local Sizzler franchisee according to procedures defined by Sizzler USA.
Explaining how this outbreak occurred, State Department of Health set forth its conclusions with surprising directness.
Based on the results of the case-control study, the test results of the opened and intact food samples from the restaurant and the conclusions of the restaurants inspections, it is most probable that the watermelon was the vehicle for infection, cross-contamination of fresh watermelon with raw meat products was the mechanism by which the vehicle became contaminated, and the raw sirloin tri-tip were the source of the E. coli O157:H7 organism in this outbreak.
The Department of Health further concluded that:
The layout of the facility and the practices of personnel may have contributed to this outbreak. The arrangement of a meat processing area (the grinding area) in close proximity to ready-to-eat food preparation areas increased the likelihood of cross-contamination.
While at first glance the circumstances of this outbreak may appear unusual, they are not. Indeed, Sizzler need only look back to 1993 when, from March through August 1993, outbreaks of E. coli O157:H7 were found in four of its Oregon and Washington restaurants. There were 39 culture-confirmed cases and 54 probable cases. See L Jackson, et al., “The Role of Cross-Contamination in 4 Chain Restaurant-Associated Outbreaks of Escherichia coli O157:H7 in the Pacific Northwest,” Arch. Intern. Med., vol. 160, Aug/ 14/28, 2000. Indeed, the cause of the four outbreaks that occurred in Sizzler restaurants in 1993 is hauntingly familiar:
Independent events of cross-contamination from beef within the restaurant kitchens, where meats and multiple salad bar items were prepared, were the likely cause of these outbreaks.
[I]nspections revealed several violations of applicable food codes and kitchen designs that were less than ideal in that raw meat was being processed and stored in close proximity to raw vegetables and other food products.
Although cross-contamination events are difficult to confirm retrospectively, we speculate that the practice of trimming, macerating, and marinating the beef tri-tips in the same kitchens used for preparation of fruits, vegetables and other salad bar items might have enhanced the potential for spatter and spillage of meat juices. According to anecdotal information from company officials and public health restaurant inspectors, [Sizzler] may have been exceptionally susceptible to cross-contamination because onsite meat cutting and large, diverse salad bar operations were combined.
Not surprisingly, after the 4 outbreaks in 1993, Sizzler is reported to have promised health department officials that it would change its practices.
Following these outbreaks and an outside review of their food-handling practices, [Sizzler] instituted a comprehensive Hazard Analysis and Critical Control Point program. [Sizzler] owned restaurants changed from using on-site meat cutting to using precut meat, as did many franchised restaurants.
Unfortunately for the victims of this most recent outbreak, the lessons learned in 1993 appear to have been forgotten.