More companies are joining the Enfamil recall of 2011. Walgreen, Kroger and Safeway have pulled the baby formula off their shelves, according to the Associated Press.

On Thursday, Supervalu confirmed it was pulling Enfamil, reported the Wall Street Journal.

Walmart was the first national retailer to pull Enfamil from more than 3,000 of its stores. The company started the recall on Monday.

The recall was prompted by the death of an infant in Missouri. The infant was fed Enfamil formula with the lot number ZP1K7G that was purchased from a Missouri Walmart, reported The AP.

Preliminary tests show he died from a bacterial infection caused by Cronobacter sakazakii.

This caused alarm because Cronobacter infection has been associated with powdered baby formula in the past, according to the Wall Street Journal.

Moreover, there is compelling evidence that milk-based powdered infant formulas are the source of infection because of a growing number of Cronobacter infections among newborn, said Missouri health authorities, reported CNN.

Customers who have purchased Enfamil with the lot number ZP1K7G should discard the product or return it to the store, stated Missouri health officials, reported CNN.

The decision of retailers to pull Enfamil from their shelves, however, is entirely voluntary. Several retailers indicated they did so out of an abundance of caution.

Health authorities are still investigating if Enfamil is responsible for the infant's death. So far, they have not made any conclusions. Enfamil maker Mead Johnson Nutrition, on its part, claimed it tested the ZP1K7G lot before sale and found no Cronobacter.

Investors of Mead Johnson Nutrition, however, are clearly concerned. On Thursday, its shares fell 10 percent while the broad stock market rallied. On Friday, its shares have plunged an additional 5 percent in the afternoon session while the broad stock market rose.