Outbreak of necrotizing enterocolitis associated with Enterobacter sakazakii in powdered milk formula

We describe an outbreak of necrotizing enterocolitis (NEC) that occurred in the neonatal intensive care unit of our hospital. A total of 12 neonates d eveloped NEC in June-July 1998. For two of them, twin brothers, the NEC tur ned out to be fatal. Enterobacter sakazakii, a known contaminant of powdere d milk formula, was isolated from a stomach aspirate, anal swab, and/or blo od sample for 6 of the 12 neonates, A review of feeding procedures revealed that 10 of the 12 patients were fed orally with the same brand of powdered milk formula, E, sakazakii was isolated from the implicated prepared formu la milk as well as from several unopened cans of a single batch, Molecular typing by arbitrarily primed PCR (AP-PCR) confirmed, although partially, st rain similarity between milk and patient isolates, No further cases of NEC were observed after the use of the contaminated milk formula was stopped. W ith this outbreak we show that intrinsic microbiological contamination of p owdered milk formula can be a possible contributive factor in the developme nt of NEC, a condition encountered almost exclusively in formula-fed premat ure infants. The use of sterilized liquid milk formula in neonatal care cou ld prevent problems with intrinsic and extrinsic contamination of powdered milk formula.