The changing epidemiology of infections at cancer hospitals.

Intensive chemotherapy regimens, widespread prophylactic and therapeutic administration of antibiotics, reliance on intravascular catheters, increased use of immunomodulators, and increased outpatient management have altered the epidemiology of infections in patients with neoplastic disease. At many centers, bacteremias due to gram-positive organisms have replaced bacteremias due to gram-negative organisms as the most frequent infections in patients with cancer. Isolation of gram-negative bacilli other than Enterobacteriaceae and Pseudomonas aeruginosa has increased in frequency, and these organisms have become important pathogens. Fungal infections have become a leading cause of morbidity and mortality, and nosocomial fungemias have become more common than nosocomial bacteremias due to gram-negative bacilli in some centers. Mycobacterium tuberculosis, Pneumocystis carinii, and rubeola virus have reemerged as disease-causing entities in patients with cancer. Multiresistant organisms have developed over the past decade. Anticipated trends in infections in patients with cancer also are discussed.