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.