Baby study links antibiotics to asthma

http://www.newscientist.com/news/pri...?id=ns99994212




Baby study links antibiotics to asthma


15:48 30 September 03

NewScientist.com news service

Babies given antibiotics during the first six months of their lives
are far more likely to develop asthma, according to a US study. Why is
not clear, but the team claims antibiotics might be partly responsible
for the steady rise in asthma cases in western countries.

A handful of studies have blamed antibiotics, but most are suspect
because they relied on the memories of parents years after events.
Instead, Christine Johnson's team at the Henry Ford Health System in
Detroit followed 448 children from birth to age seven, regularly
checking on their health.

Nearly the half of the children were given antibiotics in their first
six months, a quarter had two courses and a fifth had three or more.
At the end of the study, tests revealed that 21 of the children had
developed allergic asthma, in which attacks are triggered by
environmental factors.

Overall, children given antibiotics in their first half-year were 2.6
times more likely to develop allergic asthma, the team told a meeting
of the European Respiratory Society on Tuesday. With broad-spectrum
antibiotics, which kill a wide range of bacteria, the risk was far
higher: children were 8.9 times more likely to suffer from asthma.

Johnson speculates that the drugs disrupt the developing immune system
because they alter the bacterial communities in the gut. This might
make it more difficult for a baby's immune system to learn which
bacteria are good and which are bad.

The findings fit in with a large body of evidence on the origin of
childhood asthma, known as the hygiene hypothesis, says Thomas Kovesi
at the Children's Hospital of Eastern Ontario, Ottawa. "The cleaner
you make things, the greater the risk of allergy," he says. "The
immune system gets bored."


Pet protection


The new study also found that the more courses of antibiotics children
were given, the greater the risk. And known risk factors for asthma,
such as having a mother with asthma or having fewer than two household
pets, seemed to amplify the effect. A child who was given
broad-spectrum antibiotics and whose family had no pets faced 11.5
times the risk of allergic asthma.

But even though Johnson's study is better designed than previous ones,
not everyone is convinced. Since so many of the children being treated
with antibiotics were ill with respiratory tract infections, it might
be that the infections, not the antibiotics, triggered the asthma,
cautions Wilfried Karmaus at Michigan State University in East
Lansing.

Or it may just be that children prone to asthma are more prone to
respiratory infections. In his own unpublished study of 600 children
from birth to age three, Karmaus also found a link between asthma and
antibiotics - but it disappeared when these factors were allowed for.

But Johnson stands by her findings. Although the numbers are
relatively small, she claims the effect still holds true when all the
children with respiratory tract infections are excluded. Even children
treated for non-respiratory illnesses such as kidney infections had a
higher risk of developing allergic asthma.


Alison Motluk

"Ilena" wrote in message
...
http://www.newscientist.com/news/pri...?id=ns99994212




Baby study links antibiotics to asthma


15:48 30 September 03

NewScientist.com news service

Babies given antibiotics during the first six months of their lives
are far more likely to develop asthma, according to a US study. Why is
not clear, but the team claims antibiotics might be partly responsible
for the steady rise in asthma cases in western countries.

Key words: "might be", "partly responsible."

It may very well be that kids who are likely to have asthma also become more
symptomatic with minor respiratory infections and are prescribed more
antibiotics because they are sicker. There may be no causal role between
antibiotics and asthma.

Jeff

(...)