Health officials confirmed on Friday they've tracked the bacteria to sprouts grown at a German farm. They're still not sure exactly what kind of sprouts is to blame.
Health officials said they tracked the bacteria's path from hospital patients struggling with diarrhea and kidney failure, to the restaurants where they had dined, to specific meals and ingredients they ate, and finally back to a single farm.
The farm in question grows alfalfa, radish and onion.
The food contamination has killed at least 31 people and sickened more than 3,000.
The Associated Press contributed to this report.