Freshway Foods of Sidney, Ohio, said Thursdaythat has sickened at least 19 people three with life-threatening illness.
College students at the University of Michigan in Ann Arbor, Ohio State in Columbus and Daemen College in Amherst, N.Y., are among those affected by the outbreak, according to health departments in those states.
Vice president Devon Beer said Freshway Foods worked with the Food and Drug Administration to trace the contaminated lettuce to a Yuma grower, whom he did not identify.
The recall only applies to romaine lettuce with "best if used by" date before or on May 12, when Freshway Foods stopped buying its romaine from Yuma, Beer said. The recall also affects "grab and go" salads sold at Kroger, Giant Eagle, Ingles Markets and Marsh grocery stores.
The lettuce was sold in Alabama, Connecticut, the District of Columbia, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia, West Virginia and Wisconsin.
FDA spokesman Ira Allen would not confirm that the source was in Arizona, but said the investigation has focused on a farm.
"Experience tells us that the point of contamination is likely at the farm level, which can then be spread during the entire processing chain," Allen said.
Freshway Foods said it was recalling romaine lettuce sold under the Freshway and Imperial Sysco brands. No contamination was found at the company's processing plant, according to the FDA.
The New York state Public Health Laboratory discovered the contamination in a bag of Freshway Foods shredded romaine lettuce on Wednesday. Local authorities had been investigating an outbreak for several weeks. The bag of lettuce came from a processing facility that was also linked to the illnesses, the FDA said. The agency would not disclose the name of that facility.
The most common strain of E. coli found in U.S. patients is E. coli O157. The CDC said the strain linked to the lettuce, E. coli 0145, is more difficult to identify and may go unreported.
E. coli infection can cause mild diarrhea or more severe complications, including kidney damage. The three patients with life-threatening symptoms were diagnosed with hemolytic uremic syndrome, which can cause bleeding in the brain or kidneys.
It was not immediately clear why students on college campuses were sickened. Freshway Foods said the lettuce was sold to wholesalers, food service outlets, in-store salad bars and delis.
Susan Cerniglia, spokeswoman for the public health department in Washtenaw County, where the University of Michigan is located, said it doesn't appear that students who were sickened ate the contaminated food on campus. It is believed they may have been sickened at local restaurants, she said.
The health department in Erie County, N.Y., issued an alert late last month that linked at least one diagnosis of E. coli to a student who ate at a Daemen College dining facility. The alert said 12 students had become ill after eating at the school and three students were hospitalized.
Department official Kevin Montgomery said one case of E. coli was confirmed at the college and a second was suspected. All the students have recovered, he said.
Jose Rodriguez of Columbus Public Health said that not all of those sickened in Ohio ate on Ohio State's campus.
Rodriguez said 15 people took ill in the Columbus area, and there were seven confirmed cases of E. coli. Seven people were hospitalized, including five students at Ohio State. He said most people have recovered but two haven't been able to return to work.