Aetiology of community-acquired pneumonia in hospital treated patients.

From May 1982 a prospective 1-year study of adult patients with community-acquired, radiologically verified, hospital treated pneumonia was performed at the Department of Infectious Diseases, Orebro Medical Center Hospital, Orebro, Sweden. The study included 147 patients with a median age of 71 years. Special efforts to diagnose a pneumococcal aetiology were accomplished by antigen detection of the pneumococcal C-polysaccharide (PnC) in sputum and saliva samples and by serological methods for determination of antibody titres against PnC. A pneumococcal aetiology was established in 46.9% of the patients, including 8.1% with double infections. Altogether Haemophilus influenzae A virus were noted in 9.5%, respectively, Mycoplasma pneumoniae in 5.4%, legionnaires' disease in 2.7% and Branhamella catarrhalis in 2.0%, whereas enteric gram-negative bacilli as aetiological organisms were not found in any patient. These findings imply that penicillin should still be the first drug of choice in hospitalized adult patients with community-acquired pneumonia in Sweden.