RT Book, Section A1 Morris, Alison A1 Masur, Henry A2 Jameson, J. Larry A2 Fauci, Anthony S. A2 Kasper, Dennis L. A2 Hauser, Stephen L. A2 Longo, Dan L. A2 Loscalzo, Joseph SR Print(0) ID 1155971544 T1 Pneumocystis Infections T2 Harrison's Principles of Internal Medicine, 20e YR 2018 FD 2018 PB McGraw-Hill Education PP New York, NY SN 9781259644016 LK accessmedicine.mhmedical.com/content.aspx?aid=1155971544 RD 2024/10/06 AB Pneumocystis is an opportunistic pathogen that is an important cause of pneumonia in immunocompromised hosts, particularly those with HIV infection (Chap. 197), organ transplants, or hematologic malignancies and those receiving high-dose glucocorticoids or certain immunosuppressive monoclonal antibodies. Pneumocystis was discovered in rodents in 1906 and was initially believed to be a protozoan. Because Pneumocystis cannot be cultured, our understanding of its biology has been limited, but molecular techniques have demonstrated that the organism is actually a fungus. Formerly known as Pneumocystis carinii, the species infecting humans has been renamed Pneumocystis jirovecii.