Bacteria-SIDS connection identified

Monash University researchers have confirmed a link between bacterial infections and sudden infant death syndrome (SIDS).

By studying lambs, the team has found that even mild infections triggered high levels of a brain steroid that could make babies more sleepy and difficult to wake up.

PhD student Saraid Billiards said the brain steroids, known as neurosteroids, were known to have sedative and anaesthetic properties.

In her work, which has been accepted for publication in the international journal Paediatric Research, Billiards found mild bacterial infection caused neurosteroid levels to soar and that the lambs subsequently became extremely drowsy and difficult to wake.

"Lambs that had just a slight infection were drowsy and not interested in feeding but control lambs with no infection were restless and quite active," she said.

"It could be that when babies suffer even a mild infection their brain steroid levels increase, they become drowsy and they have blunted responses to everything that's happening around them.

"If they develop breathing problems while they're asleep that cause their blood oxygen to fall they don't have the appropriate arousing response that allows them to wake."

The National Health and Medical Research Council funded the work, which was released to coincide with SIDS and Kids Red Nose Day, which helped raise money for research into the disease.

Billiards said that while a link between bacterial infection and SIDS had long been established, this was the first work to demonstrate why it could cause babies to die.

One of Billiards' supervisors, principal research fellow in physiology Dr David Walker, said the findings pointed to the possibility of using drugs to block the sedating effect of the neurosteroids.

"In our research we also found evidence to suggest that low blood oxygen levels, which are common in babies with poorly developed lungs, cause some drowsiness," Walker said.

"When those low blood oxygen levels were combined with the increased brain steroid concentrations due to infection, the lambs became remarkably drowsy, there was a real additive effect."