The Minnesota Department of Health has confirmed two more cases of foodborne illness caused by a strain of E. coli bacteria.

That increases the number of confirmed cases associated with the outbreak to 15.

Officials say 12 of the people sickened by the infection reported eating at one of 8 Applebee’s locations in Minnesota between June 23rd and June 29th. The Health Department says the restaurants possibly linked to the outbreak are located in four suburbs of the Twin Cities, along with Duluth, Willmar, Bemidji, and Monticello.

Officials previously said the restaurant chain was cooperating with the investigation and had voluntarily removed an Oriental chicken salad item from its menus as a precaution.