WASHINGTON (CNN) -- Federal and state health officials said Monday that salmonella linked last week in Minnesota to King Nut peanut butter was caused by the same strain of bacteria responsible for an ongoing outbreak of 410 salmonella cases in 43 states.
Salmonella bacteria are transmitted to humans by eating contaminated foods.
The infection may have contributed to three deaths, the Centers for Disease Control and Prevention said Monday.
"Preliminary analysis of an epidemiologic study conducted by CDC and public health officials in multiple states comparing foods eaten by ill and well persons has suggested peanut butter as a likely source," the disease agency said in a written statement. "To date, no association has been found with common brand names of peanut butter sold in grocery stores."
A spokesman for the Food and Drug Administration said Monday that the agency has been collaborating with the CDC, the U.S. Department of Agriculture and public health officials in many states to investigate the outbreak of infections due to Salmonella enterica serotype Typhimurium.
"This new information from Minnesota will not change what we are currently doing as part of the investigation," said FDA spokesman Michael Herndon. 
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The Minnesota bacteria were linked last week to institutionally distributed peanut butter, sold under the King Nut brand name.
In one of the Minnesota patients, a 70-year-old female nursing home resident, the infection proved fatal, said Doug Schultz, a Minnesota public health department spokesman.
"We do not know to what extent the salmonella contributed to the death," said Schultz, who added that the patient had other underlying illnesses.
Virginia Health officials confirm that two of the three deaths linked to the salmonella outbreak were from their state. Although she could not provide a lot of information due to privacy laws, Michelle Peregoy, a spokesperson for the Virginia Department of Health tells CNN that one person who died was over age 65 and from the Southwest part of the state, the other person who died was a younger adult between the ages of 25-64.
As with the Minnesota patient, both Virgina patients had underlying illnesses, which means they had weakended immune systems. Very young people, older people and those with compromised immune systems are the most vulnerable to severe side effects, including death.
Late last week, King Nut Companies, based in Ohio, recalled King Nut peanut butter. President and CEO Martin Kanan said the product is manufactured by a Lynchburg, Virginia-based company, Peanut Corporation of America.
"King Nut took this action as soon as it was informed that salmonella had been found in an open five-pound tub of King Nut peanut butter," the company said Saturday in a posting on its Web site.
King Nut, which distributes peanut butter through food service accounts, does not sell directly to consumers.
Kanan said King Nut has asked customers to stop distributing peanut butter with lot codes beginning with "8" and has canceled orders with the manufacturer.
The first cases nationwide were reported September 3, but most occurred between October 1 and December 31, the CDC said last week. About 18 percent of cases were hospitalized as a result of their illness, and patients have ranged from 2 months to 98 years of age.
California has reported the highest case count with 55, followed by Ohio with 53, Massachusetts with 39, Minnesota with 30 and Michigan with 20.
The other 37 states are each reporting from one to 19 cases.
The seven states that have reported no cases connected to the outbreak are Montana, New Mexico, Louisiana, Mississippi, South Carolina, Florida and Alaska.
Strains of salmonella linked to outbreaks in the past have been traced to contaminated eggs, meat, poultry, vegetables, pet food and peanut butter.
Contaminated tomatoes were blamed for an outbreak in the fall of 2006 caused by salmonella Typhimurium, which sickened at least 183 people in 21 states. Most people suffered from diarrhea and fever for about a week. No one is known to have died in that outbreak.
Salmonella infections can be treated with antibiotics, though some strains are resistant to these drugs, according to the CDC. Most people infected develop diarrhea, fever and abdominal cramps within a few days of infection and the illness can last up to a week.
Most recover without treatment, but some may suffer dehydration and, in severe cases, require hospitalization.
Children, senior citizens, people with chronic illnesses and those with weak immune systems tend to be at highest risk for complications, according to the National Institutes of Health.
CNN's Louise Schiavone and Miriam Falco contributed to this story.
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