Cot death explained?

2008-05-30 07:20

London - A baffling phenomenon known as Sudden Infant Death Syndrome is one of the leading causes of death for children under one. Now, British researchers say they may have found a contributing factor: bacteria.

A study published on Friday in the medical journal, The Lancet, found potentially dangerous bacteria present in half of babies who died suddenly and unexpectedly between 1996 and 2005 at a London hospital.

"This may be another piece to the puzzle," said Marian Willinger, a SIDS expert at the United States' National Institute of Child Health and Human Development who was not connected to the British study.

A SIDS diagnosis means that no other cause of death can be found in an otherwise healthy infant who dies suddenly in his/her sleep. In the United States, SIDS kills more than 2 000 infants every year. In the United Kingdom, more than 200 children die every year of the syndrome.

Researchers at the Great Ormond Street Hospital for Children in London examined the cases of 546 infants who died suddenly and unexpectedly between 1996 and 2005. They focused on bacterial samples taken from 470 autopsies.

Scientists found bacteria such as staphylococcus aureus and E coli in 181 babies, or half of those whose deaths were unexplained. Similar bacteria were found in 44 babies who died of other causes. Most of the bacteria were detected in the babies' lungs and spleens.

The researchers cautioned, however, that while more dangerous bacteria were found in the SIDS babies, that does not necessarily mean the bacteria were responsible.

Vulnerable to bacterial infections

"We don't know whether it's a cause or if it's identifying another potential risk factor," said Dr Nigel Klein, professor of infection and immunity at Great Ormond Street Hospital and one of the paper's authors.

He said that the higher level of bacteria might be evidence of another condition that killed the baby, such as a room that was too hot or had poor ventilation. Or it may have been coincidental.

"The bottom line is that it's different and further work needs to be done to clarify what the link is," he said.

Klein and colleagues will next examine why the bacteria were present in the babies and whether the bacteria might be producing any deadly toxins.

Others thought the research bolstered the hypothesis that infections may be to blame for at least some SIDS cases. The syndrome typically strikes when babies are between eight to ten weeks old.

At birth, mothers transfer some of their antibodies to their babies. But when babies are from eight to ten weeks old, the maternal antibodies have nearly run out and the babies typically have not started producing enough of their own.

That could make them particularly vulnerable to bacterial infections, said James Morris, a pathologist at the Royal Infirmary in Lancaster, who co-authored an accompanying commentary in The Lancet.

"The study is a good indicator that certain bacteria might be involved in causing sudden infant deaths," he said.

Willinger thought that bacterial infections in infants might simply aggravate other risk factors for SIDS, such as smoke exposure or babies sleeping on their stomachs. "The bacteria in combination with other co-factors might push these babies over the edge," she said.

Experts said that current recommendations to parents to prevent SIDS remain unchanged. Parents should refrain from smoking, put babies to sleep on their backs and avoid putting too many blankets on them, even if they have a fever.

- AP