Taco Bell says independent testing has ruled out all its ingredients except one -- scallions -- as a possible source of E. coli that has sickened more than 60 people in the Northeast.
The green onions were pulled from the company's 5,800 restaurants nationwide on Wednesday after preliminary tests showed scallion samples contained the E. coli strain.
Scallions from a California farm are considered as the source of the outbreak, although health officials are still investigating.
But as a precaution, Taco Bell has switched produce suppliers for the Northeast.
The Centers for Disease Control and Prevention has said it expects the number of cases to grow.
As of Saturday, the agency had counted 61 confirmed cases in five states, most of them in New Jersey, New York, Pennsylvania and Delaware.