 Enterobacter sakazakii in Powdered Infant Formula
Introduction 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. Infants (less than 1 year of age) at greatest risk for E. sakazakii
infection are neonates (up to 4 weeks of age), particularly pre-term infants,
low-birth-weight infants or immunocompromised infants.
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 4oC 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.
Risk Assessment Section
July 2004
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