Pneumocystis jirovecii
（重定向自Pneumocystis carinii）
![](/Images/godic/202502/03/Pneumocystis_carinii_010257.jpg")
Pneumocystis jirovecii is a yeast-like fungus of the genus Pneumocystis. The causative organism of Pneumocystis pneumonia, it is an important human pathogen, particularly among immunocompromised hosts. Prior to its discovery as a human-specific pathogen, P. jirovecii was known as P. carinii.