London, May 30 : Researchers have identified two common bacteria that may contribute to the increasing number of cot deaths.
A team from the Great Ormond Street Hospital have identified two bacteria Staphylococcus aureus and Escherichia coli, which are a prominent cause of sudden infant death syndrome (SIDS), commonly called cot deaths.
For the study, the researchers looked at the results of autopsies of more than 500 infants who died aged between one week and one year.
They later compared the rate of infection by both bacteria in infants whose cause of death was known, and those in SIDS babies.
The findings revealed that 26 pct of the autopsies showed infection by the bacteria, whereas in the SIDS cases, the rate of infection was nearly two fold.
"What's good about this is it's a large study at one institution where all the cases were investigated in the same way, so it's enabled us to really provide harder evidence," New Scientist quoted Marian Malone, one of the study's co-authors, as saying.
However, George Haycock, scientific adviser to the UK's Foundation for the Study of Infant Deaths cautions that there isn't just one answer to the SIDS mystery.
"This is certainly not the cause of SIDS, which is almost certainly multifactorial," he said.
"Even in the cases where no cause can be identified, there may be multiple factors operating," he added.
The researchers believe that bacteria grow in the upper respiratory tract of babies, where it discharge toxins that lead to death.
"It's a theory that would fit the facts," said Malone.
"We know that prone sleeping - sleeping on the front - can increase the number of pathogenic organisms in the upper airway. We know that if the mother has been smoking during pregnancy, it can alter the immune response [to toxins]," Malone added.
The genetic differences among SIDS babies also determine immune response.
Jim Morris, a pathologist at the Royal Infirmary, Lancaster, UK said that it's another piece of evidence fitting in with lots of other evidence that has been gathering, pointing to these bacteria.
"None of this is proof positive, but its another important step to understanding what's going on," he added.
The study is published in journal Lancet.