More than 4.5 million Americans develop community-acquired pneumonias
(CAP) annually. Of these, about 1 million persons are hospitalized, ge
nerating more than $4 billion in medical expenses.(2, 16) Despite the
availability of dozens of antibiotics and an ever-increasing array of
interventions, CAP is an important cause of morbidity and ranks sixth
in cause-specific mortality for Americans.(9) Over the last three deca
des, much has been learned about the epidemiology and pathogenesis of
CAP, and from this body of knowledge, several preventive interventions
have emerged. This article describes the preventive strategies of imm
unization, immunoprophylaxis, and chemoprophylaxis in accord with cont
emporary understanding of pulmonary host defenses and the pathogens th
at are the principal causative agents of CAP. Emphasis is on CAP in th
e setting of normal care provided by the primary care internist.