Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) is a form of pneumonia caused by the yeast-like fungus Pneumocystis jirovecii. It is an opportunistic infection that occurs in individuals with weakened immune systems, such as those with HIV/AIDS, cancer, or those undergoing immunosuppressive therapy.

History

The organism Pneumocystis jirovecii was first described in 1909 by Carlos Chagas and was initially thought to be a protozoan. It was later reclassified as a fungus. The disease became widely recognized during the HIV/AIDS pandemic in the 1980s, as it was a common opportunistic infection in patients with AIDS.

Pathophysiology

Pneumocystis jirovecii is an atypical fungus that primarily infects the lungs. It is transmitted through airborne spores. In healthy individuals, the immune system can control the infection, but in immunocompromised individuals, the organism can cause severe pneumonia. The fungus attaches to the alveoli in the lungs, leading to inflammation and impaired gas exchange.

Clinical Presentation

Patients with PCP typically present with:

• Progressive dyspnea (shortness of breath)
• Non-productive cough
• Fever
• Fatigue

In severe cases, patients may experience respiratory failure.

Diagnosis

Diagnosis of PCP is challenging and often involves:

• Chest X-ray: May show diffuse bilateral interstitial infiltrates.
• CT scan: Can reveal ground-glass opacities.
• Bronchoalveolar lavage: A sample of fluid from the lungs is examined for the presence of Pneumocystis jirovecii.
• Polymerase chain reaction (PCR): Can detect the DNA of the organism.

Treatment

The primary treatment for PCP is the antibiotic trimethoprim/sulfamethoxazole (TMP-SMX). For patients who cannot tolerate TMP-SMX, alternatives include pentamidine, dapsone, or atovaquone.

Prophylaxis

Prophylactic treatment is recommended for individuals at high risk of PCP, such as those with a CD4 count below 200 cells/µL. TMP-SMX is also used for prophylaxis.

Prognosis

With appropriate treatment, the prognosis for PCP has improved significantly. However, it remains a serious condition, especially in patients with advanced immunosuppression.

Also see

• Opportunistic infection
• HIV/AIDS
• Fungal pneumonia
• Immunosuppression