Diagnosis and antibiotic treatment of community-acquired pneumonia.

Only a few pathogens cause most community-acquired pneumonias. In outpatients, treatment is empiric, based on the results of chest films, leukocyte counts, and Gram's stains (if available). Antibiotics must always cover pneumococci and should cover Mycoplasma pneumoniae in young adults and during epidemic periods. A follow-up chest film in smokers and those older than 40 years is strongly recommended. In inpatients, the evaluation and treatment are tailored to individual cases. A search for a wider range of causes, using invasive tests if necessary, is undertaken, and all likely pathogens should be covered with the initial antibiotic therapy.