Researchers have stumbled across a variation of the E.coli O157:H7 bacterium that can withstand the internal temperatures and cook times that are recommended to restaurants as ways of safeguarding guests.
Biologists at the University of Alberta in Canada identified the variant after a student discovered live E.coli in a meat sample that had been cooked to an internal temperature of 140 degrees for 70 minutes. The researchers initially thought the student had made an error in testing, according to local press reports. But subsequent experiments showed the E.coli could withstand temperatures of up to 160 degrees—the threshold at which the bacteria is guaranteed by most experts to be eliminated—even if cooked for more than an hour.
The researchers compared the makeup of the heat-resistant bacteria to the genetic profiles of strains that have been recorded in a databank because they were known to sicken people. About 2% of the E.coli involved in the outbreak matched the heat-resistant variety.
Researchers at the university are now trying to determine what temperature will kill the more resistant strain, according to the press reports.
The U.S. government has not yet commented publicly on the discovery.