Atypical pathogen pneumonia.

The term atypical pathogens has been applied in recent years to Chlamydia pneumoniae, Mycoplasma pneumoniae, and the various species of Legionella. The incidence of pneumonia caused by these pathogens has increased with the development of specific diagnostic techniques. Atypical pathogen community-acquired pneumonia demonstrates a broad spectrum of severity from a mild disease not requiring hospitalization to adult respiratory distress syndrome necessitating mechanical ventilation. The clinical, radiological, and laboratory manifestations of the disease are similar to those of community-acquired pneumonia caused by other pathogens, and reliable etiological differentiation cannot be based on these factors alone. The possibility of shortening treatment time, at least in some patients, by antibiotic therapy with the new macrolides has been added to standard therapeutic regimens with erythromycin, tetracyclines, or quinolones.