Pneumocystis jiroveci

Pneumocystis jiroveci 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, Pneumocystis jiroveci was known as Pneumocystis carinii.

Taxonomy

Pneumocystis jiroveci is a member of the fungal genus Pneumocystis. The species name jiroveci is named after the Czech parasitologist Otto Jirovec, who first identified Pneumocystis as a cause of pneumonia in humans.

Morphology

Pneumocystis jiroveci is a small, unicellular organism that can exist in both a trophozoite (trophic) form and a cyst form. The trophic form is smaller and replicates via binary fission, while the cyst form is larger and can contain up to eight intracystic bodies.

Pathogenesis

Pneumocystis jiroveci is the causative organism of Pneumocystis pneumonia (PCP), a severe lung disease that primarily affects immunocompromised individuals, such as those with HIV/AIDS, those undergoing chemotherapy, and those receiving immunosuppressive therapy following organ transplantation. The organism is believed to be transmitted via airborne droplets.

Diagnosis and Treatment

Diagnosis of Pneumocystis jiroveci infection is typically made via identification of the organism in sputum or bronchoalveolar lavage fluid. Treatment typically involves a combination of trimethoprim and sulfamethoxazole, although other antifungal agents may be used in cases of allergy or resistance.

See Also

• Pneumocystis
• Pneumocystis pneumonia
• Fungi
• Pathogen
• Immunocompromised