An E. coli outbreak this past summer in Chicago that sickened more than 100 people was likely caused by fresh cilantro, according to the city’s final outbreak report, even though no food from the implicated restaurant tested positive for the pathogen.
The report from the Chicago Department of Public Health, obtained through a Freedom of Information Act request, also shows 16 of 40 food-handling employees of Carbón Live Fire Mexican Grill tested positive for E. coli soon after the restaurant’s two locations voluntarily closed for cleaning July 1.
However, the health department downplays the significance of the employee test results.
“Among the 40 food handlers interviewed none reported any history of gastrointestinal illness in the two weeks preceding or during the outbreak period, though absenteeism was reported for one. Nearly all food handlers had stool tests performed within one week after the restaurant closure,” according to the report.
Lab tests confirmed 69 people were sickened during the outbreak, with another 37 probable cases. Of the sick people, 22 had symptoms so severe that they required hospitalization. Illness onset dates ranged from June 3 to July 23.
Five of the 69 people confirmed with infections from the outbreak strains of E. coli reported they did not eat at the Carbón Live Fire Mexican Grill and five others were not available for interviews.
Cilantro is the suspected source of the E. coli based on percentages of sick people who ate menu items made with the fresh produce item. Inspectors collected 12 food items, including cilantro, but none of the food returned positive results for E. coli bacteria. The cilantro was sourced from Illinois and Mexico, according to traceback information provided to the health department.
“Lettuce was associated with illness in both multivariable models but was consumed by only 44 percent of cases,” according to the health department report.
“In comparison, cilantro was consumed by 87 percent of cases, and either cilantro or salsa fresca (which included cilantro) were consumed by 95 percent of cases.”
The report references “several critical violations” observed during a July 1 inspection, such as improper temperatures for several food items including red and green salsas, tequila lime sauce, raw fish, guacamole and cheese. Inspectors also noted improper hand hygiene practices among food handlers.
During the voluntary closure of the two Carbón Live Fire Mexican Grill locations the restaurants were cleaned and staff was trained in proper food handling and hand hygiene, according to the report. The the south and west side restaurants re-opened on July 9 and 29, respectively.
Health officials praise the restaurant owner in the report. The owner not only closed temporarily, he also pulled Carbón from the high-profile Taste of Chicago event.
“Closure of the restaurant during the early stage of the investigation prevented additional cases of illness from occurring,” according to the conclusion of the report.
The report’s conclusion also suggests that all of the cilantro and other food samples that tested negative for E. coli may not have been representative of food that sickened customers.
“(E. coli) was not isolated from cilantro or cilantro-containing food items collected from the restaurant or the restaurant’s distributor. Inability to isolate STEC from food samples may have been hindered by imperfect sensitivity of testing, imperfect representativeness of food samples, or turnover of produce items through the distribution chain leading to items no longer being contaminated at the time of collection,” according to the report conclusion, which waffled on the topic of whether food handlers played a role.
“Additionally, cross-contamination during food preparation and transmission by food handlers who were found to have STEC infection likely contributed to the outbreak.”
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