The FDA and the Centers for Disease Control and Prevention (CDC) along with state and local officials are investigating two separate outbreaks of E. coli O26 infections that have been linked to food served at Chipotle Mexican Grill restaurants in several states.

As of January 27, 2016, a total of 55 people infected with the outbreak strain of STEC (Shiga toxin producing E. coli) O26 from a total of 11 states in the larger outbreak: California (3), Delaware (1), Illinois (1), Kentucky (1), Maryland (1), Minnesota (2), New York (1), Ohio (3), Oregon (13), Pennsylvania (2), and Washington (27). There have been 21 reported hospitalizations. The majority of these cases were reported from Oregon and Washington during October 2015.

In December 2015, the CDC reported five people infected in three states with a different, rare strain of STEC O26: Kansas (1), North Dakota (1), and Oklahoma (3). Interviews were conducted with five ill people, who all reported eating at Chipotle Mexican Grill restaurants. There were no reports of hemolytic uremic syndrome (HUS) and no deaths in either outbreak. .

Investigators used whole genome sequencing, an advanced laboratory technique, to get more information about the DNA fingerprint of the STEC O26 bacteria causing illness in both outbreaks. Whole genome sequencing (WGS) was performed on STEC O26 isolates from 36 ill people from the first outbreak. All 36 isolates were highly related genetically to one another. This provided additional evidence that illnesses outside the Pacific Northwest, were related to the illnesses in Washington and Oregon. WGS was also performed on STEC isolates from four people in the second outbreak. All were highly related to one another, although not to the isolates from the first outbreak.

Chipotle Mexican Grill closed 43 restaurants in Washington and Oregon in early November 2015 in response to the initial outbreak. All these restaurants reopened in November 2015. Chipotle Mexican Grill worked in close consultation and collaboration with health officials throughout the investigation to determine whether it was appropriate to reopen these restaurants. Chipotle reports taking the following actions, among others, prior to opening:

  • Confirming that all microbial testing performed by the company did not yield E. coli (more than 2,500 tests of Chipotle’s food, restaurant surfaces, and equipment all showed no E. coli)
  • Confirming that no employees in these restaurants were sickened from this incident
  • Expanded testing of fresh produce, raw meat, and dairy items prior to restocking restaurants
  • Implementing additional safety procedures, and audits, in all of its 2,000 restaurants to ensure that robust food safety standards are in place
  • Working closely with federal, state, and local government agencies to ensure that robust food safety standards are in place
  • Replacing all ingredients in the closed restaurants
  • Conducted additional deep cleaning and sanitization in all of its closed restaurants (will conduct deep cleaning and sanitization additionally in all restaurants nationwide)

The FDA conducted tracebacks of multiple widely-distributed ingredients. Traceback can be difficult with Mexican-style foods given they are often complex dishes containing multiple ingredients. No product of interest was identified. Even without a definitive item to follow, the FDA traced back to their origins some widely distributed ingredients in an effort to identify a source for the outbreak. Unfortunately, the distribution path did not lead to an ingredient of interest.

The FDA also conducted investigations of some suppliers, but did not find any evidence that those suppliers were the source of the outbreak. Ultimately, no food item has been identified as causing the outbreak, and by the same token, no food has been ruled out as a cause.