Atypical pneumonias: therapeutic possibilities.

The atypical pneumonia syndrome is characterized by systemic complaints rather than respiratory symptoms. The causative pathogens include Mycoplasma, Chlamydia, Legionella and respiratory viruses (influenza, adenovirus, respiratory syncytial virus). The reported incidence of disease caused by these pathogens in community-acquired pneumonias varies from study to study. As most of these pathogens are intracellular, the antibiotics used in the treatment of atypical pneumonia are those able to penetrate into cells. Empirical antimicrobial therapy consists of macrolides (erythromycin or some of the newer agents such as roxithromycin, azithromycin or clarithromycin) or tetracyclines (e.g. doxycycline). In cases of severe legionellosis and in immunocompromised and critically-ill patients, the macrolides are sometimes given in combination with rifampicin. Promising alternatives are some of the newer fluoroquinolones (e.g. ofloxacin, pefloxacin) in the treatment of legionellosis.