Infection with Chlamydophila pneumoniae or Mycoplasma pneumoniae has been linked to asthma. There is evidence to suggest that persistent infection with these organisms might lead to an increase in the severity of asthma. beta-Lactam antibiotics have not been shown to be beneficial in the treatment of asthma but several studies have indicated that macrolides and related antibiotics might be useful both for the treatment of chronic asthma and for acute exacerbations. However, these observations need to be confirmed in further studies. It is not clear whether any effect that these antibiotics has is a result of antimicrobial actions against organisms such as C. pneumoniae or whether it is due to their anti-inflammatory action.