Acute community-acquired pneumonias.

Of 81 adult patients with community-acquired pneumonia, bacterial infections were found in 37%, mycoplasma and viral infections in 21%, and tuberculosis in 6%; no pathogen could be identified in 46% of cases. More than one agent was identified in 12% of patients. Streptococcus pneumoniae, the most common pathogen, was found in 63%, Haemophilus influenzae in 26,7%, Staphylococcus aureus in 6,7%, and other Gram-negative organisms in 10% of patients with proven bacterial pneumonia. Most clinical and radiographic features were of little value in differentiating between different aetiological agents, but Gram-stained sputum gave a valuable early guide to therapy in 60% of cases of proven bacterial pneumonia. Blood culture was positive in 13,6% of cases. All the organisms conformed to their usual sensitivity patterns. Since Strept. pneumoniae is the predominant pathogen, penicillin should be the drug of choice in the immediate 'blind' treatment of community-acquired pneumonia.