Disease-causing microbes found in baby food

New Scientist reports from The American Society for Microbiology 104th Annual Conference that baby food has been found to contain worrying levels of disease-causing microbes. A bacterium called Enterobacter sakazakii, which has been linked to a handful of fatal outbreaks of meningitis at children's hospitals in the US and Europe was of most concern.

Enterobacter sakazakii has been found in powdered infant formula before, but a new UK study is the first to detect it in dried infant food.

Premature babies and those with a weakened immune system are at particular risk. Even the babies who survive an infection often suffer brain damage, says Carol Iversen, who studies the bacterium at Nottingham Trent University in the UK. "Very few recover fully," she says.

Iversen and her colleagues have undertaken an extensive survey of powdered infant formula, dried infant food and milk powder from seven European countries, the US, South Korea and South Africa.

They analysed more than 200 samples from 110 different products for the presence of a variety of bacteria. Eight out of 82 powdered infant formula samples contained stomach bacteria, as did 12 out of 49 dried infant food samples.

Thirteen of the bacterial species they identified, including E. sakazakii, are members of the Enterobacteriaceae, a family associated with hospital-acquired infections.

Iversen stresses that manufacturers do not claim the products are completely free of pathogens, but she points out that many parents and nurses assume they are. "There is a misconception that infant formula powder is a sterile product," she says.
In a separate study, the team looked at the best ways to prepare and store infant formula made from powder to minimise the risk of infection. They found that the number of bacteria doubled every 10 hours in the fridge, while at room temperature it took just half an hour for numbers to double.

This means that any formula left out overnight could go from containing very few bacteria to harbouring dangerous levels, says Stephen Forsythe, who led the team. As a father himself, Forsythe sympathises with parents who want to prepare bottles ahead so that night feeds go as quickly as possible.

"At three o'clock in the morning an extra three minutes is a long time," he says. But Forsythe urges parents to resist the temptation to prepare formula in advance.