[Pneumonia in clinical practice: diagnosis and therapy]

Outpatients with pneumonia are usually treated empirically. Therefore, the knowledge of the most important causative agents is a prerequisite for the 'educated guess'. With a broad microbiological evaluation, the etiology of a pneumonia can be detected in only half of the cases. In outpatients, 30% of the causative agents are viruses, 45% 'atypical bacteria' such as Mycoplasma sp. and Chlamydia pneumoniae, and 25% pneumococci and Hemophilus. In hospitalized patients, pneumococci and Hemophilus cause 60%, and 'atypical bacteria' only 25% of the community acquired pneumonias. The most relevant microbiological examination in outpatients is the Gram stain of the sputum. The sputum culture is seldom useful and sometimes even misleading, especially if the result is not interpreted in connection with the Gram stain. The most appropriate treatment of outpatients without underlying disease is a macrolide. In patients with chronic bronchitis, alcoholism or preceding influenza infection, amoxicillin/clavulanic acid or a new oral cephalosporin is the best choice. The detection of risk factors for fatal outcome is important for the decision to admit the patient to a hospital.