Four more major retailers are following Walmart's example by removing cans of infant formula from their shelves in light of the death of a 10-day-old Missouri infant from what early tests indicate was a bacterial infection.
Supervalu Inc., Walgreen Co., Kroger Co. and Safeway have decided to clear their shelves of 12.5 ounce cans of Enfamil Premium Newborn formula, lot number ZP1K7G. The batch has come under scrutiny after the infant, identified by other media outlets as Avery Cornett of Lebanon, Mo., had allegedly consumed the formula before he became sick. Preliminary tests show he developed a rare infection from Cronobacter sakazakii, a bacteria that has previously been found in powdered infant formula. Thus far, health officials have not confirmed that the formula in question was the source of the baby's infection.
"Out of an abundance of caution, we are removing the formula from certain stores," SuperValu spokesman Mike Siemienas told ABCNews.com on Friday. "We will hold these products from sale until we receive additional guidance from regulatory authorities and the manufacturer."
Siemienas said that while the company did not yet have exact figures, he expects that "hundreds of stores" will be affected. Among Supervalu's subsidiary grocery retailers that removed the product from shelves are Shaw's, Shop 'n Save, Jewel-Osco, Acme supermarkets, Farm Fresh, and Albertson's in southern California.
Kroger officials told the Associated Press that they withdrew the formula from properties in Arizona, Indiana, New Mexico and the mid-Atlantic region.
Walgreen Co. spokesman Jim Cohn confirmed that the company's stores have pulled the formula from store shelves, though he said it was unclear how many stores would be affected under the directive. "We are awaiting further clarity from the manufacturer and FDA."
Messages left with Safeway were not immediately returned, though a company spokeswoman told the Associated Press Friday that their affected stores were primarily in the Chicago area.
Walmart was the first to act this week when it pulled the formula from the shelves of 3,000 of its stores nationwide.
"This is not a formal government recall. We just did this out of an abundance of caution, and we're currently holding the product until the investigation is complete. The product could possibly be returned to shelves at a later date," a Walmart spokesperson told ABC News Radio on Thursday.
Health officials say customers who purchased the formula should discard it or return it to the store.
The Missouri Department of Health and Senior Services said in a statement samples of the formula were sent to the Centers of Disease Control and Prevention and the Food and Drug Administration for testing.
The FDA said so far, they "don't have anything that indicates this is linked to Enfamil." However, the agency is testing samples from the open packet of formula fed to the infant, an unopened packet of the formula and the water used to mix the formula. They expect results by the middle of next week.
Avery is the second infant to develop a Cronobacter sakazakii-related infection in a Missouri hospital in the past month, the department said on its web site. The second infant recovered.
A spokesman for Mead Johnson Nutrition, the manufacturer of Enfamil formulas, said on Thursday that the company routinely tests its formula for Cronobacter.
"The batch of our product used by the child's family tested negative for Cronobacter when it was produced and packaged, and that has been reconfirmed from our batch records following this news," he said.
Cronobacter sakazakii, once known as Enterobacter sakazakii, is a bacteria found in powdered infant formula as well as in plant material and the environment, according to CDC.
The World Health Organization says there have been about 120 documented cases of Cronobacter sakazakii infection worldwide. In 50 to 80 percent of cases, powdered infant formula is the source of Cronobacter illness. There have been several outbreaks of disease in neonatal intensive care units around the world.
Newborns are at highest risk for serious illness from the bacteria, which can cause meningitis and bloodstream infections. The fatality rate in infants is very high.
"It's introduced somehow during the manufacturing process, but they haven't quite figured out how that happens," said Dr. William Schaffner, chairman of the department of preventive medicine at Vanderbilt University Medical Center. "Infant formula has all kinds of nutrients, so it's a particularly appropriate environment for these bugs to grow [in]."
According to WHO, the bacteria could be introduced in three ways: through the raw ingredients before production, through contamination after pasteurization and through contamination during preparation of the formula by caregivers.
Referring to published case studies, Schaffner said many of the infants became ill because the formula wasn't prepared properly. Powdered infant formula is not sterile and must be handled carefully to avoid contamination.
"Caregivers sometimes haven't followed the instructions very meticulously," he said.
He said in order to minimize the risk of infection, caregivers should take careful precautions.
"Sterilize bottles, spoons and nipples in boiling water. Infant formula should be freely prepared for each feeding, and remaining milk should be discarded. Water should be boiled and allowed to cool before preparing the formula," Schaffner explained.
In addition to meningitis and bloodstream infections, Cronobacter sakazakii can cause necrotizing enterocolitis, a condition in which the intestinal lining dies off.
Symptoms of necrotizing enterocolitis include bloody stool, diarrhea, vomiting, lethargy and intoleratnce to feeding.
Symptoms of meningitis in infants include high fever, neck and body stiffness, constant crying and seizures.
Additional reporting by ABC News' Brian Hartman and Josh Cohan. Associated Press reports contributed to this report.