ABSTRACT

I. Introduction The population of immunocompromised hosts (ICH) susceptible to pulmonary infection continues to grow. This is due to prolonged survival of patients with cancer, wider use of solid organ transplants (SOT) and hematologic stem cell transplants (HSCT), and introduction of new, targeted but powerful immunosuppressive agents for hematologic, autoimmune, dermatologic, and renal diseases (1-3). Strategies to reduce infection, including prophylactic agents and nonmyeloablative regimens for HSCT, are being employed, but pneumonia is still common (4). Some infections, such as opportunistic fungal pneumonia, are increasing in frequency, and new pathogens are emerging (5-7). When respiratory failure develops from pneumonia in the ICH, mortality is high (2,8).