Pneumocystis jiroveci pneumonia, formerly known as Pneumocystis carinii pneumonia (PcP), occurs when immune function is suppressed to a certain threshold.
Mortality rate: 30-60%
Pneumocystis, initially considered to be a protozoan, later has been assigned to the kingdom of fungi, due to its high genetic sequence homology with these organisms, as demonstrated by molecular studies (Edman et al.1988). Nevertheless, despite many similarities, Pneumocystis is an atypical fungus which differs in several respects from its relatives. One of such distinctive features, among others, is the presence of cholesterol in the Pneumocystis cell membrane, instead of ergosterol, which is the target of amphotericin B and ketoconazols. Therefore these drugs, commonly used as therapeutics in infections caused by other fungi, are ineffective in treatment of symptoms triggered by P. jirovecii (Kaneshiro et al. 1994).
Bronchoscopy with BAL (most sensitive)
Diffuse bilateral infiltrates (DIAGNOSTIC)
Gomori’s methamine silver (GMS) staining: Cysts resemble black-coloured crushed ping pong balls against the green background