Interventions designed to reduce known risk factors for sudden infant death syndrome, such as putting babies to sleep on their backs or convincing moms to stop smoking, are credited with lowering SIDS deaths by more than 50% in the U.S. between the mid- and late-1990s.
But no one really understands why the interventions work, SIDS researcher James A. Morris, MD, of the Royal Infirmary Lancaster, tells WebMD.
"We told people to do this, but we couldn't tell them why," he says.
Bacterial Infection and SIDS
The new research explored the old idea that bacterial infection is to blame for at least some cases of sudden, unexplained death among babies.
Pediatric pathologist Neil J. Sebire, MD, and colleagues from London's Great Ormond Street Hospital for Children reviewed the autopsy results of close to 500 babies who died suddenly and unexpectedly.
The researchers grouped the cases by whether the autopsies revealed no obvious cause of death, evidence of bacterial infection as a likely cause, or evidence of another cause that was not bacterial.
Bacterial samples taken at autopsy were also grouped by whether the bacteria were associated with obvious causes of death by infection or whether the bacteria could cause rapid death without an obvious infection.
Two bacteria in the latter group -- Staphylococcus aureus and Escherichia coli -- were found to be more common than expected in babies whose deaths could not be explained.
Sixteen percent of samples from infants whose deaths remained unexplained after autopsy contained the staph bacteria, compared with 9% of infants whose deaths were explained but not related to infection. And 6% of samples from the former group contained E. coli, compared with just 1% of samples from the latter.
The study and an editorial by Morris and colleague Linda Harrison, MD, appear in the May 30 issue of The Lancet.