Around 2,500 infants in the U.S. die without warning each year and their deaths remain largely unexplained - classified as SUDDEN INFANT DEATH SYNDROME, or SIDS.
Doctors in Australia compared autopsy results from babies who died of SIDS and those who died of other causes.
Not surprisingly, they discovered that many infants who died of infections had evidence of bacteria in their systems - but they also found that 1 in 10 SIDS babies tested positive for bacteria. The research examined post-mortem reports on 130 babies who died of SIDS, 32 who died suddenly as a result of infection, and 33 who died of non-infectious causes.
This was followed by an analysis of bacterial isolates from normally sterile sites (such as heart blood, spleen, or cerebrospinal fluid) in all the babies. Infection at a sterile site was rare in the babies who died of non-infectious causes but was present in 20 percent of the babies with sudden infection and 10 percent of the SIDS babies.
The infections were caused by Staphylococcus aureus, a dangerous bacteria that can produce potentially deadly toxins. The relatively high proportion of SIDS babies in this study who had S. aureus in sterile sites suggests that a number of them died due to the infection, the researcher concluded.
Researchers theorize that infants may be particularly vulnerable to bacterial infection between 8 and 10 weeks -- a peak risk period for SIDS -- because of their immature immune systems.
Experts say widespread antibiotic treatment for babies IS not the answer - more research is needed to find the best way to prevent these infections.
Parents should focus on PROVEN ways to reduce SIDS - always put babies to sleep on their backs, in a crib with no loose pillows or blankets, and keep the home SMOKE free.
The study was published online ahead of print in the Archives of Disease in Childhood.
Previous research has suggested that immune responses to bacterial infections or toxins can cause a "chemical storm" in infants that result in sudden death. The study author said the cause of death may need to be reconsidered in cases of SIDS where S. aureus is found in sterile sites.