In April 2002, a batch of powdered infant formula suspected to have caused infection in a premature infant was recalled in the United States (US) and Australia after the Centers for Disease Control and Prevention of the US unveiled that the infection might be associated with the presence of Enterobacter sakazakii in the said powdered infant formula. Further reports showed that E. sakazakii might be related to severe infections in infants especially premature neonates.

E. sakazakii

E. sakazakii is an opportunistic pathogen of emerging public health concern. It is a gram-negative, rod-shaped, facultatively anaerobic bacterium. E. sakazakii is a rare cause of neonatal meningitis and sepsis.

The World Health Organization (WHO) and the Food and Agriculture Organization (FAO) of the United Nations had jointly convened an expert meeting on E. sakazakii in powdered infant formula in February 2004. The expert meeting concluded that intrinsic contamination of powdered infant formula with E. sakazakii had been a cause of infection and illness in infants, including severe disease, and can lead to serious developmental sequelae and death.

Occurrence of E. sakazakii

Little is known about the ecology of E. sakazakii. However, E. sakazakii has been found in manufacturing equipment which is a potential source of contamination for powdered infant formula after pasteurization.

Risk of E. sakazakii contaminated Powdered Infant Formula

E. sakazakii infection is an opportunistic infection and is only rarely reported. In the past four decades, around 30 sporadic cases and outbreaks of neonatal E. sakazakii infection were reported worldwide. The cases were mostly associated with hospitalized newborn infants, particularly premature infants or infants with underlying medical conditions. Powdered infant formulas were the implicated sources of infection in some neonatal intensive care unit outbreaks.

Advice to the public

There is ample evidence that breast-feeding is better than bottle-feeding for the health of babies. For mother who cannot breastfeed or chooses not to breastfeed for any reason, it should be noted that powdered infant formula is not a sterile product.

Reconstituted powdered infant formula should be consumed within two hours after preparation but not longer than four hours. Any reconstituted powdered infant formula stored at room temperature over four hours should be discarded.

Reconstituted milk not for immediate consumption should be stored under refrigeration at 4^oC or below but for not more than 24 hours.

For high-risk infants who are not breastfed, caregivers are encouraged to use whenever possible and feasible, commercially sterile liquid formula or formula which has undergone an effective decontamination procedure such as using boiling water in reconstituting powdered infant formula or heating reconstituted milk. However, reconstituting powdered infant formula by boiling water or heating reconstituted milk may result in some nutrient loss. Also formula prepared in this way should be cooled and handled appropriately as there is a risk of burns from mishandling of boiling or hot water/formula.