http://news.bmn.com/news/story?day=030704&story=1

3 July 2003 17:00 GMT

by Helen Dell

Standard asthma drugs exacerbate a common bacterial infection linked with increased asthma severity, report Japanese researchers. Treating asthmatics for the infection improves their condition, they say.

The bacteria Chlamydophila pneumoniae (formerly Chlamydia pneumoniae) causes acute and chronic respiratory infections in humans, and such infections are found more frequently in the respiratory tract of asthmatics than in healthy people. "Asthma is a very common disease, and C. pneumoniae is a very common infection," said Kazunobu Ouchi, a professor at Kawasaki Medical School in Okayama, corresponding author on the study. "[C. pneumoniae] greatly exacerbate the severity of asthma attacks," he said.

Ouchi and colleagues examined the link between the bacteria and asthma by testing the effects of common asthma drugs on the growth of C. pneumoniae in cell culture. They found that when the bacteria were exposed to glucocorticoids at therapeutic concentrations normally inhaled by patients, bacterial growth doubled. The data are published in the Journal of Infection and Chemotherapy. The findings are worrying, says Ouchi, because these steroid inhalants are now the worldwide recommended treatment for patients with persistent asthma.

The news comes as no surprise to David Hahn, clinical professor of family medicine at the University of Wisconsin and one of the first researchers to link C. pneumoniae with asthma. "Chronic infection [with C. pneumoniae] is common, and it is easy to see that immunosuppressants [such as glucocorticoids] might allow reactivation of a dormant infection," he said. "But it's unclear what the consequences of this might be because there is plenty of evidence that inhaled glucocorticoids help asthma."

He thinks that although the steroids suppress the asthmatic symptoms, they might also affect the long-term course of the disease. Chronic infection with C. pneumoniae would cause continual lung inflammation, he says, acting like an ever-present allergen. Suppressing the symptoms while encouraging the infection might cause a lot of damage over the long term. This is an important issue that has had little recognition or funding from the US National Institutes of Health (NIH), he says.

Ouchi agrees. The steroid inhalants are very good at treating asthma, he says, but they enhance growth of C. pneumoniae, so the treatment regimen must be re-examined.

Ouchi's team has already begun to look at the effects of treating C. pneumoniae infection in asthma patients. "Our preliminary data indicate that ... drugs active against C. pneumoniae have favorable effects on the severity of the asthma," he said.

Hahn has also done a pilot study in a small group of persistent asthmatics, and found that six weeks of anti-chlamydial treatment produced a dramatic improvement in the symptoms of half the patients.

At the moment, diagnosing C. pneumoniae infection requires a sample of lung tissue. "That's impossible in a practical sense," said Hahn, "but if [anti-chlamydial drugs] help half of the patients, it might not be necessary to diagnose infection, we could just treat everybody."

© Elsevier Limited 2003