An Irish-British research team has said its finding that the lungs of healthy asthmatics have high levels of bacteria could help the development of new treatments.
Doctors say it may provide the missing link to explain what causes some patients to have an overactive immune response, sparking an asthma attack.
Up to now allergies have been blamed for many asthma cases and normal lungs were always thought to be sterile.
The research was conducted by a team at the Department of Respiratory Medicine at Connolly Hospital in Dublin and the National Heart and Lung Institute at Imperial College London.
Professor Conor Burke, respiratory consultant at Connolly Hospital, said that the team had found around 2,000 bacteria for every square centimetre of lung.
He said the Irish-British team had found the first evidence to show this and its original findings were recently confirmed by a large multicentre US study.
The news that both the lungs of healthy adults and healthy asthmatics have large amounts of bacteria was a surprise.
"Our findings may be the missing link - the greatly increased bacterial load in asthmatics may be the trigger to the enhanced immune response which causes asthma", Prof Burke said.
The finding may provide a new target for potential drug treatments for both asthma and bronchitis.
Emergency departments deal with around 20,000 patients with asthma in Ireland each year.
Over 500,000 people have asthma and it costs the State around €500,000 to treat each year.
