http://news.bmn.com/news/story?day=020426&story=1

25 April 2002 18:00 GMT

by Julie Clayton, BioMedNet News

Milan - The mystery of what causes Sudden Infant Death Syndrome, also commonly known as Cot Death, may have been solved with the identification of a toxin of the bacterium E.coli in the blood of babies who have died from SIDS.

The findings open the way to developing a vaccine to prevent SIDS, according to a new study, which its Australian researchers presented here this afternoon at the 12th European Congress of Clinical Microbiology and Infectious Diseases.

The toxin, known as curlin, was present exclusively in the serum of 68 SIDS babies, and none of the 60 normal healthy babies or 17 dead control babies, reports Paul Goldwater, of the Microbiology and Infectious Diseases Department of The Women's and Children's Hospital in Adelaide.

"This indicated that curlin could be responsible for SIDS deaths given the fact that curlin causes shock in laboratory mice, and profound effects on the clotting system and on blood vessels," he said. "Curlin could thus explain all the pathological findings in SIDS."

But Goldwater’s claim has a long way to go before it is accepted by other SIDS researchers, already weary with past claims for bacterial involvement, according to at least one audience member, Rolland Mollby, professor of bacteriology at the Karolinska Institute in Stockholm.

"We really want to know what has happened to these babies that explains why they are so susceptible - and before you show that, we won’t believe you!" Mollby told Goldwater.

The news that E.coli is involved is not in itself surprising, as this and other bacteria have already been implicated in SIDS, according to another SIDS researcher, Richard Sherburn, a research fellow in the Department of Biological Sciences at De Montfort University in Leicester.

But the identification of curlin toxin as a factor is a welcome advance, notes Sherburn. "That does sound like a significant piece of work, and yet more evidence for the infection model of SIDS," he told BioMedNet News.

Sherburn himself has unpublished findings that suggest how E.coli, Staphylococcus aureus and Bordetella pertussis could colonize the polyurethane foam of cot mattresses to levels sufficient to infect babies.

Other recent findings point to an infectious agent as the cause of SIDS, including work at the University of Edinburgh by Carol Blackwell, now retired to Australia, who found a reduced incidence in babies who had been immunized with the diptheria, tetanus, pertussis (DTP) vaccine.

In addition, pathology findings indicate that SIDS babies have died from a shock-like process, as they are frequently found to have skin hemorrhages and unclotted blood. Their serum (but not that of normal babies) is toxic to cultured cells and mice, indicating the presence of a toxin, according to Goldwater.

Curlin is already known to have a number of effects, including the triggering of inflammation, but exactly how these may cause SIDS is unknown, he says.

The toxin comes in two forms – soluble, which was the form detected in the blood of SIDS babies, and polymerized into filaments.

Goldwater’s team found E.coli, which produced the filamentous form, in the intestines of all the SIDS babies examined, 94 out of 94, in 13 out of 17 (76.5%) dead control babies, and in 74 of 92 (80.4%) of normal healthy controls. This is a significant difference, says Goldwater.

He cannot explain why the soluble form of curlin was found only in the serum of SIDS babies. Its absence from the serum of healthy controls could explain why they have not died of SIDS, he suggests.

To Sherburn, the ratios are surprisingly high and warrant further investigation. "I'd be a bit concerned at the number of positives of the controls," he said.

ALL INFORMATION, DATA, AND MATERIAL CONTAINED, PRESENTED, OR PROVIDED HERE IS FOR GENERAL INFORMATION PURPOSES ONLY AND IS NOT TO BE CONSTRUED AS REFLECTING THE KNOWLEDGE OR OPINIONS OF THE PUBLISHER, AND IS NOT TO BE CONSTRUED OR INTENDED AS PROVIDING MEDICAL OR LEGAL ADVICE.  THE DECISION WHETHER OR NOT TO VACCINATE IS AN IMPORTANT AND COMPLEX ISSUE AND SHOULD BE MADE BY YOU, AND YOU ALONE, IN CONSULTATION WITH YOUR HEALTH CARE PROVIDER.