TRENTON, N.J. ? Taco Bell announced Saturday that tests have ruled out all its ingredients except one – scallions – as a possible source of a harsh strain of E. coli that has sickened more than 60 people in the Northeast.

The green onions had been pulled from the company’s 5,800 restaurants nationwide on Wednesday after it said preliminary tests showed scallion samples contained the E. coli strain, and it no longer plans to sell them, said Rob Poetsch, a spokesman for the Irvine, Calif.-based company.

Poetsch said samples from the company’s entire menu were collected from restaurants in several states for the independent testing done by Certified Laboratories in Plainview, N.Y.

Scallions from a California farm were 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, even though it has no indication that any of the suppliers were associated with the illness.

“We’ve taken this health issue very seriously and are extremely concerned for all those who are ill. Our company has moved quickly to safeguard the health of our customers and employees,” said Greg Creed, president of Taco Bell Corp.