Mead Johnson, the largest U.S. baby formula maker, saw its shares fall nearly 15 percent last week after Wal-Mart Stores Inc
U.S. and local health officials are looking into the source of the bacteria, and are looking at several types of formula besides Enfamil.
Mead Johnson said on Sunday that a new round of testing of samples of Enfamil formula showed the product was safe.
Mead Johnson shares were at $68.35 in premarket trade, up 4.7 percent.
(Reporting By Martinne Geller in New York, editing by Dave Zimmerman)