A bacterial infection may be an overlooked cause of sudden infant death syndrome, an Australian study suggests.

Researchers analyzed autopsy reports on 130 babies who died of SIDS, 32 who had died suddenly as a result of infection, and 33 who had died of non-infectious causes, such as car collisions.

Sudden Infant Death Syndrome (SIDS), also known as crib death, refers to the sudden and unexpected death of an apparently healthy infant under one year of age.

'As part of our research, we found two-thirds of SIDS infants actually carry these lethal toxins in their intestines.'— Dr. Paul Goldwater

"We believe that these pathogens are actually causing infection and they may be the cause of SIDS," said study author Dr. Paul Goldwater of the Women's and Children's Hospital and the University of Adelaide.

"We found them in about a quarter of the cases of sudden infant death. Staph always is one of the leading ones and we found it in about 10 per cent."

The researchers also analyzed bacteria from normally sterile sites, such as the spleen, of the SIDS babies and compared it with 65 other babies.

Infections at the sterile areas were rare in infants who died from other causes.

But the sterile tissue was infected in nearly one in five babies who died suddenly from infection, and one in 10 SIDS babies, the researchers report in the online version of the Archives of Disease in Childhood.

During life, bacterial contamination of a sterile site signals systemic infection.

Many of the infections were linked to golden staph bacteria, the researchers said.

"What's of particular note is that staph aureus, this golden staph, very commonly carries lethal toxins. And as part of our research, we found two-thirds of SIDS infants actually carry these lethal toxins in their intestines," said Goldwater.

Goldwater recommended that post-mortems in SIDS cases look more carefully for the bacteria in sterile sites before declaring a cause of death. Previously the bacteria may have been dismissed as contamination.

The researchers had to look at cases over a 25-year period to find data to analyze.

Health Canada advises parents to lower risk of SIDS by:

• Not smoking around the baby.
• Putting babies to sleep on their backs.
• Avoiding dressing the baby in too many clothes or adding too many covers to prevent overheating.
• Breastfeeding, which may give some protection.

Each week, three babies die of SIDS in Canada, according to the Public Health Agency of Canada.

With files from the Australian Broadcasting Corp.