Baby killing bacterium lurks
in powdered milk formula

Known since 1958, E. sakazakii infection is rare,
but not rare enough

By Graham Furness

A potentially lethal bacterium has been found in powdered baby milk formula from four out of four factories tested by researchers, according to a study in The Lancet. Enterobacter sakazakii, considered an emerging infection, was also present in the products of four out of five adult food factories tested.

E. sakazakii infection remains rare, but has caused several outbreaks of severe meningitis among neonates since it was first observed in 1958. Mortality rates have been as high as 80%. In March 2002, a number of outbreaks in American hospitals provoked the Center for Communicable Diseases to issue an advisory warning that the bacterium might be lurking in powdered baby milk. A month later, the maker Wyeth Nutritionals was obliged to recall a batch of formula after E. sakazakii was found at a manufacturing plant in Georgia.

The mounting suspicions about baby formula led a team of Dutch researchers to investigate the problem at its source. With funding from food giant Nestle, they examined environmental samples from four baby formula factories, five other food factories, and 16 households. The bacterium was isolated in five of the 16 households, and in no fewer than eight of the nine factories. The article does not specify which, if any, of the factories are operated by Nestle.

The researchers wrote: "The presence of E. sakazakii in factories producing milk powder, cereals, chocolate, potato flour and pasta, as well as in domestic environments, strongly indicates that it is a widespread micro-organism. This should be taken into account in the design of effective control measures."

The research suggests a far wider spread of the bacterium than anyone had suspected. Since it doesn't generally cause symptoms in adults, the finding of E. sakazakii in adult food factories is unlikely to cause any lost sleep among infectious disease specialists, but the baby formula finding confirms the suspicions of experts, who have suspected a link ever since 1988. In that year, a study in the Journal of Clinical Microbiology found E. sakazakii in 20 of 141 baby formula samples taken from 35 different countries.

Dr Jeffrey Farber, from the Bureau of Microbial Hazards at Health Canada, said that a growing number of outbreaks of infection among premature babies provided "compelling evidence" that milk-based powdered infant formulas are implicated. Premature babies are often given formula milk in an effort to stimulate growth. Among older infants and full-term babies, only those with depressed immune systems have so far proved vulnerable to E. sakazakii meningitis.

Dr Farber said that while liquid formulas are heat-treated at high temperatures, powdered versions are not, and that blenders used to prepare the feeds later on could easily become a reservoir of infection for entire wards.

He added that it might be sensible to minimize the amount of time between the preparation of the formula and its consumption by the baby. "The fact that the disease it causes has a very high mortality rate and that the organism affects very young infants is a cause for concern."