Pneumocystis jiroveci pneumonia

Whilst the organism Pneumocystis carinii is now referred to as Pneumocystis jiroveci, the term Pneumocystis carinii pneumonia (PCP) is still in common use

• Pneumocystis jiroveci is an unicellular eukaryote, generally classified as a fungus but some authorities consider it a protozoa
• PCP is the most common opportunistic infection in AIDS
• all patients with a CD4 count < 200/mm³ should receive PCP prophylaxis

Features

• dyspnoea
• dry cough
• fever
• very few chest signs

Pneumothorax is a common complication of PCP.

Extrapulmonary manifestations are rare (1-2% of cases), may cause

• hepatosplenomegaly
• lymphadenopathy
• choroid lesions

Investigation

• CXR: typically shows bilateral interstitial pulmonary infiltrates but can present with other x-ray findings e.g. lobar consolidation. May be normal
• exercise-induced desaturation
• sputum often fails to show PCP, bronchoalveolar lavage (BAL) often needed to demonstrate PCP (silver stain shows characteristic cysts)

PA chest film showing hypoinflated lung volumes and increased bibasilar ground glass opacities. There is an incidental right subclavian central venous catheter present - e Image used on license from Radiopaedia