ABSTRACT
I. Introduction Advances in modern medicine notwithstanding, respiratory tract infections remain a major source of morbidity, mortality, and medical costs in our society. In fact, as a consequence of the current capacity of modern medicine to apply novel life-sustaining therapies, a number of new patient populations have emerged with specific impairments in their ability to fight infection, and these individuals have an enhanced risk for one specific infection: pneumonia. Patients at risk for pneumonia include not only previously healthy individuals but also those with increased threat, such as the elderly-especially those with complex chronic illness-and those with novel forms of immunosuppressive illness as the result of organ transplantation or an HIV infection.
