Minnesota health officials have confirmed two more cases of E. coli associated with Applebee's restaurants, expanding an outbreak first reported Monday to 15 cases statewide.

Twelve of the 15 people became infected after eating at Applebee's restaurants between June 23 and June 29, according to the Minnesota Department of Health, and one of the two new patients reported eating the restaurant's Oriental Chicken Salad. But because not all the cases have been linked to Applebee's, it's possible the outbreak is connected to a more widely distributed food source.

The two new cases, both an unusual strain known as E. coli O111, match the genetic fingerprint of the bacteria associated with the initial cases. Both patients have recovered.

An investigation into the source of the infection, led by the state Department of Agriculture, is continuing. The two new cases expand the span of time during which people were infected, initially thought to be June 24-27, which makes it slightly harder to pinpoint the source, according to Stephanie Meyer, a Health Department epidemiologist.

Meyer said it's too early to tell whether the additional cases indicate the potential for a much larger outbreak.

"We almost always expect to see a few cases trickle in," after an outbreak is first reported, Meyer said. "It could mean there's still a produce item out there or something that still has the potential to cause illness."

The E. coli infection can cause stomach cramps and severe diarrhea. Most patients recover in five to 10 days, but the disease can cause serious complications, particularly in the elderly, young children and people with weakened immune systems.

With the new cases, the updated list of Applebee's locations linked to the illness is Blaine, Duluth, Roseville, Willmar, Woodbury, Monticello, Bemidji and New Hope. The restaurant announced Monday that it voluntarily pulled the Oriental Chicken Salad from its menu, which several of the infected patients reported eating. It also withdrew cabbage, carrots and almonds — ingredients in that salad — from other menu items.

A number of people have called the Health Department reporting intestinal symptoms since Monday, but most do not appear linked to the outbreak.

Officials are asking anyone who has eaten at an Applebee's and experienced E. coli symptoms to contact the Health Department at 1-877-366-3455.