Which organism is the etiologic agent of Pneumocystis jirovecii pneumonia?

Which organism is the etiologic agent of Pneumocystis jirovecii pneumonia?

• A. Candida albicans
• B. Pneumocystis jirovecii
• C. Histoplasma capsulatum
• D. Aspergillus fumigatus

Answer: (B)

Pneumocystis jirovecii pneumonia is caused by Pneumocystis jirovecii, an opportunistic fungal organism that primarily affects the lungs in people with compromised immune systems. When asked for the etiologic agent, you’re identifying the organism responsible for causing the disease, which is Pneumocystis jirovecii. The other fungi listed cause different infections—Candida albicans leads to candidiasis, Histoplasma capsulatum to histoplasmosis, and Aspergillus fumigatus to aspergillosis—so they are not the cause of Pneumocystis pneumonia. It’s also helpful to know that this disease used to be called Pneumocystis carinii pneumonia, but the organism in humans is now named Pneumocystis jirovecii, which aligns with the disease name.

Pneumocystis jirovecii pneumonia is caused by Pneumocystis jirovecii, an opportunistic fungal organism that primarily affects the lungs in people with compromised immune systems. When asked for the etiologic agent, you’re identifying the organism responsible for causing the disease, which is Pneumocystis jirovecii. The other fungi listed cause different infections—Candida albicans leads to candidiasis, Histoplasma capsulatum to histoplasmosis, and Aspergillus fumigatus to aspergillosis—so they are not the cause of Pneumocystis pneumonia. It’s also helpful to know that this disease used to be called Pneumocystis carinii pneumonia, but the organism in humans is now named Pneumocystis jirovecii, which aligns with the disease name.