Pneumocystis jirovecii pneumonia

What it is

Pneumocystis jiroveci looks like a protozoon but is genetically a fungus. It is killed by antibacterials and by an antiprotozoal agent, but not by antifungals.

The pneumonia it causes is still called PCP, and it is the most common opportunistic infection in AIDS. It is almost always in an HIV patient and can be seen in patients on corticosteroids; in HIV it is one of the pulmonary opportunistic infections a patient is at risk for.

Causes and risk

HIV is where it is met, and the risk is tied to the CD4 count: prophylaxis is given for HIV patients when the CD4 count is below 200, and patients with HIV require prophylaxis to prevent Pneumocystis jirovecii pneumonia with CD4 counts below 200/mm3. Corticosteroids are the other name on the list.

How it presents

It is indolent in HIV, or acute respiratory failure in the immunocompromised. Fever, a dry nonproductive cough and progressive dyspnea are what is seen, with low oxygen levels. On examination there is tachypnea, and crackles are heard in the lungs.