title: Pneumonia in the immunocompromised host.
abstract: OBJECTIVE
  Novel treatment modalities for previously fatal diseases, including newer chemotherapeutic and biologic agents and the expansion of the indications for solid organ and stem cell transplantation, have resulted in prolonged patient survival and a significant increase in the population of immunocompromised hosts (ICHs).
  
  
  RESULTS
  This review discusses the increasing spectrum of opportunistic infections in the ICH, the general approach for early diagnosis and treatment of pulmonary infections in this population, and the current and novel diagnostic modalities available to establish a rapid and specific microbiologic diagnosis, focusing on recent controversies and advances.
  
  
  CONCLUSIONS
  Early diagnosis and prompt initiation of effective therapy for infection help reduce morbidity in ICHs. Advances in diagnostic assays using nonculture-based methods, such as nucleic acid amplification, may allow for earlier targeted therapy. Invasive procedures including bronchoscopy and biopsy remain essential and should be vigorously pursued in ICHs given the broad differential diagnosis of possible pulmonary pathogens in this population, and the need to establish a specific diagnosis to allow accurate targeted therapy.
authors.affiliation: aDivision of Infectious Diseases, Brigham and Women's Hospital bDepartment of Medical Oncology, Dana-Farber Cancer Institute cHarvard Medical School, Boston, Massachusetts, USA.
authors.forename: Alyssa R
authors.initials: AR
authors.lastname: Letourneau
authors.forename: Nicolas C
authors.initials: NC
authors.lastname: Issa
authors.forename: Lindsey R
authors.initials: LR
authors.lastname: Baden
mesh_terms: D016026:Bone Marrow Transplantation; D003937:Diagnosis, Differential; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D016867:Immunocompromised Host / Q000276:immunology*; D008172:Lung Diseases, Fungal / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D008297:Male; D009894:Opportunistic Infections / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D016377:Organ Transplantation; D018579:Patient Selection; D011014:Pneumonia / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D018570:Risk Assessment