Pneumocystis

Pneu·mo·cys·tis .n(y)ü-mə-'sis-təs n

1) a genus of microorganisms of uncertain affiliation that are usu. considered protozoans or sometimes fungi and that include one (P. carinii) causing pneumonia esp. in immunocompromised individuals

2) PNEUMOCYSTIS CARINII PNEUMONIA

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n.

a genus of protozoans. The species P. carinii causes pneumonia in immunosuppressed patients, usually following intensive chemotherapy (see also AIDS). Pneumocystis carinii pneumonia (PCP) is fatal in 10-30% of cases if untreated, but it can be overcome with high doses of co-trimoxazole or pentamidine.

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Pneu·mo·cys·tis (noo″mo-sisґtis) [pneumo- + cyst] a genus of yeastlike fungi infecting virtually all mammalian species and having a predilection for the lungs, where it is primarily an alveolar pathogen, although disseminated infection may occur in severely immunocompromised hosts. The various species are host-specific, and organisms cannot be grown outside of an infected host.