How Safe are Infant Formulas?

Enterobacter sakazakii causes invasive infection with high mortality rates in neonates. Enterobacter sakazakii is a gram-negative rod within the family Enterobacteriaceae, genus Enterobacter. The organism was called “yellow-pigmented Enterobacter cloacae ” until 1980 when it was renamed Enterobacter sakazakii. Urmenyi and Franklin (1) reported the first two known cases of meningitis caused by E. sakazakii in 1961. Subsequently, cases of meningitis, septicemia, and necrotizing enterocolitis due to E. sakazakii have been reported worldwide (2). When meningitis occurs, severe neurological complications, including cerebral abscess formation, are common, and death occurs in 33%—80 % of cases. Enterobacter sakazakii has been detected in tins and packages of powdered infant formula. The pathogen is able to grow in infant formula milk during storage at refrigeration temperatures and attach to infant-feeding equipment, which may become reservoirs of infection. Enterobacter sakazakii appeared to be one of the most thermo tolerant organisms (3,4). Risk for infection might depend on several factors, including the number of bacteria present in the product, handling after preparation, and underlying patient characteristics (e.g., immunosuppression, prematurity, or low birth weight (2). Evidence In one of the prospective study (5), a quantity of dehydrated powdered infant formula was prepared to contain Enterobacter sakazakii strain 607 at approximately 106 CFU/ml when rehydrated, according to the manufacturer’s instructions. The survival of the microorganism in the dry formula was followed for 2 years, during which samples periodically were rehydrated and analyzed for viable Enterobacter sakazakii. During the initial 5 months of storage at room temperature, viable counts declined approximately 2.4 log cycles. During the subsequent 19 months, the concentration of viable E. sakazakii declined an additional 1.0 log cycle. These results indicate that a small percentage of E. sakazakii cells can survive for extended periods in dehydrated powdered infant formula