UPDATED at 6:46 p.m. with new information

The E. coli bacteria that has sickened at least 22 people across the St. Louis region may be linked to produce at local grocery stores.

The confirmed E. coli cases include 16 in St. Louis County, two in Jefferson County, two in St. Charles County, one in St. Louis City and one in St. Clair County. At least six people have been hospitalized.

Health officials confirmed the source of the E. coli 0157 is food-borne, but said the investigation is ongoing and all of the affected people have not been interviewed. Grocery stores have not been asked to pull any food from shelves or salad bars, but may have voluntarily done so.

Schnucks stores, on the advice of their food safety team, voluntarily replaced some produce from salad bars and shelves.

"Once we heard that the health department had declared an outbreak, we took some proactive steps with our food safety team to switch products out that recent history told us could be potential sources," said Schnucks spokeswoman Lori Willis. "I would venture to guess we're not the only ones doing it."

Schnucks on Clayton Road in Richmond Heights voluntarily pulled all strawberries, lettuce and croutons out of its salad bar on Wednesday, according to deli manager Mike Reardon.

"It was just a precautionary move," Reardon said, adding, "As far as I know, there haven't been any problems with anything we've sold."

Reardon said he knew of no one who had called to complain about getting sick after eating food from the store.

A customer, Ken Gurney, said Thursday that he had not heard about the E. coli outbreak. Gurney wondered if the problem might extend beyond the salad bar. "Don't they stock the salad bar with products from the shelves?" he asked.

Reardon later said that the voluntary removal was limited to products available at the salad bar.

Another Schnucks store, Culinaria in downtown St. Louis, put a sign up on empty shelves reading "Due to a voluntary recall on pre-packed lettuce, we will not be able to produce these pre-made salads. Be assured quality is our main concern. All of the lettuce on the salad bar is fresh and not involved with the recall."

Willis said pre-packed lettuce was not necessarily a concern, but the smaller Culinaria store has different methods of stocking their salads. She added that no products were involved in a recall.

Management at the Dierbergs supermarket in Brentwood said it had pulled no items and had no plans to do so.

Mercy Hospital in Creve Coeur has so far treated six patients for the bacterial infection that causes intestinal symptoms. The E. coli 0157 strain does not respond to antibiotics so patients have to let the infection run its course, a hospital spokeswoman said.

Lindsay Schuessler, 25, has been hospitalized at Mercy since Saturday. Doctors there confirmed Schuessler was infected with the E. coli bacteria, her father said.

County health officials visited Schuessler's home in University City and removed some produce including strawberries that she had purchased at Schnucks, Rick Schuessler said.

The Missouri Department of Health and Senior Services is assisting local health officials in the investigation and the Centers for Disease Control and Prevention also has been notified.

People should thoroughly cook food, especially meat, wash produce thoroughly and wash their hands and cooking equipment to avoid cross-contamination.

People experiencing gastrointestinal symptoms, including severe stomach cramps, diarrhea or nausea, should seek medical attention.

James Bell, of Florissant, said his 23-year-old daughter, Jasmine, has been hospitalized since Saturday with what hospital and health officials told him was a confirmed E. coli case. Jasmine Bell started feeling sick during the middle of last week.

James Bell said Thursday evening his daughter remains hospitalized at Christian Hospital in north St. Louis County and is having a hard time keeping down solid foods. She is receiving fluids and remains on pain medication.

"She really wants to get out of the hospital and she doesn't feel like she's getting better," James Bell said.

Bell said his daughter ate salads twice last week that she bought at the Schnucks Culinaria store in downtown St. Louis. He said he thinks both of the salads were prepackaged, purchased from the salad and deli section of the store.

Bell hopes his daughter will be released from the hospital in the coming days but said, "she's not out of the woods yet."

Health officials expect more cases to come forward because the incubation period for E. coli, between the infection and the onset of symptoms, can be as long as 10 days.