NEW YORK -- Chipotle says it is tightening its food safety standards after its restaurants were linked to dozens of cases of E. coli.
The Mexican food chain said it hired IEH Laboratories in Seattle to help improve its supply system after reports in late October that linked E. coli cases to its restaurants in Oregon and Washington. Since then, additional cases have been reported in California, Minnesota New York, and Ohio.
The Denver-based chain said the new procedures will include testing of all produce before it is shipped to restaurants, and testing to ensure quality throughout shelf life. It said it will enhance employee training for food safety and handling.
Chris Arnold, a spokesman for Chipotle Mexican Grille Inc., has said the company's local produce suppliers may not all be able to meet the new standards.
The company has not said how sales have been affected by the E. coli cases.
Word of the new testing regime came as the Centers for Disease Control and Prevention reported that the E. coli outbreak linked to Chipotle has expanded to nine states, with a total of 52 reported illnesses.
The CDC said Friday that seven additional people were sickened, including in three more states — Illinois, Maryland and Pennsylvania. The most recent illness started on Nov. 13, it said.
The majority of the illnesses have been in Oregon and Washington, where cases were initially reported at the end of October. Additional cases were later reported in California, Minnesota, New York and Ohio.
The CDC had said in late November that additional cases could be reported for illnesses that started after Oct. 31. On Friday, it said illnesses that started after Nov. 11 may not be reported yet.
The ingredient responsible for the illnesses has not yet been determined.
Chipotle said Friday that no ingredients that are likely to have been connected to the incident remain in its restaurants or supply system.