Pneumocystis jiroveci pneumonia, formerly known as Pneumocystis carinii pneumonia (PcP), occurs when immune function is suppressed to a certain threshold.
Mortality rate: 30-60%
History:
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).
Distinguish Pneumocystis sp. between fungi and protozoan features | Pneumocystis pneumonia: An update – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Distinguish-Pneumocystis-sp-between-fungi-and-protozoan-features_tbl1_7677307 [accessed 12 Feb, 2020]
Clinical features
Key differences in clinical manifestations, diagnostic strategies and outcome in HIV-positive and HIV-negative patients with Pneumocystis jirovecii pneumonia. | Liebling, M., Rubio, E.R., & Ie, S.R. (2015). Prophylaxis for Pneumocystis jiroveci pneumonia: is it a necessity in pulmonary patients on high-dose, chronic corticosteroid therapy without AIDS? Expert review of respiratory medicine, 9 2, 171-81 .
Diagnosis
Bronchoscopy with BAL (most sensitive)
Chest X-ray:
Diffuse bilateral infiltrates (DIAGNOSTIC)
Chest X-ray shows diffuse bilateral infiltrates and mild cardiomegaly. | Sabbagh, W., & Darwich, N. S. (2018). Pneumocystis Jiroveci Pneumonia and Newly Diagnosed Human Immunodeficiency Virus (AIDS) in a 63-Year-Old Woman. The American journal of case reports, 19, 927–931. doi:10.12659/AJCR.909612
CT-scan:
Transbronchial biopsy:
Gomori’s methamine silver (GMS) staining: Cysts resemble black-coloured crushed ping pong balls against the green background
(A) GMS stain of the transbronchial biopsy showing Pneumocystis organisms. (B) Transbronchial biopsy showing acute and chronic inflammation with focal organization. | Sabbagh, W., & Darwich, N. S. (2018). Pneumocystis Jiroveci Pneumonia and Newly Diagnosed Human Immunodeficiency Virus (AIDS) in a 63-Year-Old Woman. The American journal of case reports, 19, 927–931. doi:10.12659/AJCR.909612
