Pneumocystis carinii

Pneumocystis carinii (now called Pneumocystis jiroveci) is a fungus which causes Pneumocystis carinii pneumonia (PCP). It affects those with weakened immune systems such as children and the elderly, but is especially prevalent in patients with AIDS. It is diagnosed by silver staining of the sputum.

In immunocompromised patients (e.g. those on chemotherapy or AIDS with a low CD4+ count; below 200/mm3), prophylaxis with regular pentamidine inhalations or sulfamethoxazole/trimethoprim can be necessary.