Shock-like Reaction to Common Bacteria and SIDS
A number of articles hit the news the past few of days regarding shock-like reaction to common bacteria and sudden infant death syndrome. The news refers to a study Dr. Paul Goldwater presented at the European Congress of Clinical Microbiology and Infectious Diseases in Milan. The public has been on an information roller coaster, the result of an explosion of media reports. We need to help people separate myth from fact and risk factor from cause. We will post information as it becomes available to us.
Please keep the following in mind:
- Other studies have made similar claims since 1978.
- The study's author does not claim to have determined the cause of SIDS.
- When it comes to media coverage of SIDS, we often feel a sense of frustration in being confronted with misleading headlines, announcements of so-called breakthroughs and statements taken out of context.
- Please read the article, "Mass Media's" Role in SIDS Education, at <http://sids-network.org/media.htm>.
- You can search MEDLINE for bacteria and SIDS information.
We are currently gathering more information about this specific research and will keep you updated.
The AP article:
SIDS May Be Linked to Infection
04/25/2002 3:03 PM EDT
By EMMA ROSS
MILAN, Italy (AP) - Sudden Infant Death Syndrome, in which apparently healthy babies die inexplicably in their cribs, may be linked to infection with a common bacterium, preliminary research suggests.
Researchers told a conference on infectious diseases Thursday that a shock-producing byproduct of E. coli was found in the blood of all SIDS babies tested, but in none of the infants used as a comparison.
Experts not connected with the research said the toxic infection theory is plausible.
SIDS describes unexpected deaths that autopsies can't explain. Despite decades of research, scientists remain mystified by crib death, the top killer of babies aged between 1 month and 1 year in the industrialized world.
Among the threats it has been tied to are sleeping position, passive smoke exposure and genetic vulnerability. Infection is not a new idea, but this is the first time the specific E. coli protein has been implicated.
Many researchers favor a theory that brain-stem birth defects somehow affect arousal reflexes, so that babies don't wake up when breathing, heart rate, blood pressure or temperature problems arise.
However, some experts believe that such brain abnormalities may not be enough to cause death on their own.
"Mainstream researchers have concentrated on respiratory obstruction as a possible mechanism, without any evidence that would support such a mode of death," said Dr. Paul Goldwater, who presented his study at the European Congress of Clinical Microbiology and Infectious Diseases in Milan.
"Those researchers ignored autopsy findings that consistently show wet, heavy lungs in SIDS babies. This is never seen" in cases of suffocation, said Goldwater, a researcher at the Women's and Children's Hospital in North Adelaide, Australia.
Such a lung condition is often seen in cases of infection.
Autopsies also consistently show small hemorrhages on the heart and lungs - which is rare in suffocation - and the blood of SIDS babies is unclotted, which is something never seen in suffocation cases, he added.
Furthermore, he said, SIDS deaths captured on medical monitors have shown that these babies died of a shock-like process, Goldwater said.
"The serum from babies who have died of SIDS is toxic to chick embryos and mice - indicating the presence of a toxin," he said.
In his study, Goldwater tested the blood of 68 SIDS babies and 60 other babies - some of whom had died of other causes and some of whom were alive - for infections that could explain the autopsy findings in SIDS babies.
He started with the common gut germ E. coli because varieties from SIDS cases are more often toxic to cells grown in a lab than are varieties found in healthy babies.
Sometimes, E. coli bacteria produce a protein called curlin, which scientists suspect may help the bacteria compete for a foothold in the competitive germ environment in the intestines, he noted.
The bacteria itself was found in the intestines of all the SIDS babies, but only in 80 percent of the healthy babies. However, curlin was detected in the bloodstream of all 68 of the SIDS babies and none of the others, Goldwater said.
"This indicated that curlin could be responsible for SIDS deaths, given the fact that curlin causes shock in laboratory mice," Goldwater said.
Dr. Carl Hunt, director of the National Research Center for Sleep Disorders at the U.S. National Heart, Lung and Blood Institute, said Goldwater's findings do not conflict with the popular brain-stem defect theory.
The deaths might be triggered by infection, Hunt said, or might be due to a combination of genetic factors, such as a brain stem defect or an impaired immune system, and environmental factors, such as the baby sleeping on its stomach or breathing in cigarette fumes.
"The basic theory that some serious, overwhelming acutely acquired infection is the cause of SIDS is a legitimate hypothesis," Hunt said. "What we recognize today as SIDS may have a variety of different causes in individual infants."
"The extent to which infection does play a role in SIDS and in what percentage of SIDS it might play a role are important questions," Hunt said.
Comments from Dr. Carl Hunt
Monday, April 29, 2002
I have not seen the actual study yet. My comments to AP were just general background.
Numerous SIDS researchers over the years have implicated some kind of shock-like reaction to common bacteria (e.g. staph. E. coli) as a precipitating mechanism for SIDS. This is not a commonly held opinion but there are some data to indicate that it might be a relevant factor in some infants. Until the details of this study can be reviewed in detail, however, it is not known whether these data provide any new insights. If this is a valid study, it would further support a potential role for infectious agents in triggering SIDS, but it would not refute a role for the various other important risk factors for SIDS that are now well-recognized.
I Hope these comments are helpful.
Comments from Dr. Henry Krous
Monday, April 29, 2002
In a word - WOW!
Given this is an abstract, much of the data, in fact, nearly all of it is omitted, we only know the number of cases and the results, but nothing of the analytical methods, standardization of postmortem scene and autopsy investigation, definition of SIDS that was used, demographic profiles of the study and control cases, pathology findings, etc.
The introductory statement that there is no evidence of airway obstruction in SIDS is blatantly erroneous. The statement that SIDS deaths captured on memory-monitors show they die a shock-like death is excessively simplistic and overstated.
Postmortem inflammatory changes in the respiratory system in SIDS cases when compared to sudden infant deaths caused by accidents or nonaccidental trauma are similar and trivial and widely viewed as not sufficiently severe to have been lethal.
Suggesting that SIDS be renamed "infant curlism" is daring given their work is unproven, unpublished in manuscript form, to my knowledge, in peer reviewed journals, and unconfirmed!
Henry Krous, MD
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