Tests confirm that bacteria in recalled batches of contaminated peanut butter match the strain of Salmonella food poisoning that has made at least 410 people sick, health officials said on Monday.

Minnesota investigators found the bacteria in the peanut butter was a genetic match to the bacteria making the people sick.

“Minnesota Departments of Agriculture and Health lab tests conducted last week discovered Salmonella bacteria in a 5-pound (2 kg) package of King Nut peanut butter collected from a long-term care facility associated with one of the reported illnesses,” the health department said in a statement.

It said the peanut butter was the likely source of the 30 cases in Minnesota.

On Saturday Ohio-based food distributor King Nut Cos said it had contacted its customers and asked them to remove all King Nut peanut butter and Parnell’s Pride peanut butter from the market.

Solon, Ohio-based King Nut supplies peanut butter to food service companies that distribute the products to institutions like hospitals, schools, restaurants and nursing homes. The brands are not sold directly to consumers.

King Nut said it asked customers to stop distributing all peanut butter with lot codes beginning with the number eight and has canceled orders with the manufacturer, Peanut Corporation of America.

Since September, the outbreak of salmonella food poisoning has sickened at least 410 people in 43 states, according to the U.S. Centers for Disease Control and Prevention.

The CDC said preliminary analysis suggest peanut butter as a likely source of the outbreak. Common brand names of peanut butter sold in grocery stores do not appear to be associated with the outbreak, the CDC said.

U.S. Department of Agriculture, Food and Drug Administration and state health officials have been trying to trace the source of the outbreak.

An outbreak of salmonella was linked to Peter Pan brand peanut butter in 2007. ConAgra Foods Inc closed a Georgia plant after more than 300 people became ill.

Salmonella can cause abdominal cramping, diarrhea and fever and it can kill the very young and the very old.

Every year, approximately 40,000 people are reported ill with salmonella in the United States, the CDC says, but it said many more cases are never reported.

WASHINGTON (Reuters)