[Impact of Chlamydia pneumoniae infections on asthma]

VIRUSES AND BACTERIA: The fact that the airways are exposed to a large number of infectious agents could explain the frequency of respiratory infections and their causal effect in bronchial inflammation. Viruses are most often the causal agent, but the frequency of bacterial infections make them potential candidates in certain respiratory diseases. Chlamydia are particularly important due to their capacity to provoke immune dysfunction and chronic inflammation. EFFECT ON ASTHMA: It is not surprising to find biological evidence of Chlamydia pneumoniae infection in a large number of subjects who experience major degradation of their asthma because asthmatic subjects are particularly susceptible to respiratory infections and Chlamydia pneumoniae is a frequent cause of such infections. PATHOGENIC EFFECT: Finding Chlamydia pneumoniae as the causal agent in asthma is however much more surprising, with a much different consequence. There are however many epidemiological and clinical findings and case observations (Chlamydia pneumoniae asthma associations, prolonged favorable course in certain obstructive bronchial diseases after a short antibiotic regimen) as well as provocative pathophysiological data favoring this particular form of "infectious asthma".

Large-scale studies with rigorous methodology remain to be performed. The would be needed to determine the exact relationship between Chlamydia pneumoniae infections and certain types of asthma, particularly when wheezing occurs after a respiratory infection and when chronic obstruction develops. The could also determine the role of anti-Chlamydia pneumoniae antibiotics in case of obstructive respiratory failure and also determine their efficacy on long-term outcome.