Preliminary hospital tests indicated 10-day-old Avery Cornett died Dec. 18 of a rare infection caused by bacteria known as Cronobacter sakazakii.
The source of the bacteria hasn't been determined, but it can be found in powdered formula. Avery had consumed Enfamil Newborn formula.
National retailers including Wal-Mart Stores Inc., Walgreen Co., Kroger Co. and Safeway have since pulled a batch of the powdered infant formula from their shelves.
The Food and Drug Administration, the Centers for Disease Control and the Missouri Department of Health are investigating Avery's death.
Mead Johnson said Sunday it shared its test results with investigators.