• Previously thought to be Pneumocystis carinii (species that infects rats) it is now known that the human pathogen is Pneumocystis jirovecii
  • Still referred to as PCP (PneumoCystis Pneumonia)
  • Fungus based on genotypic homologies
  • Incidence has greatly decreased since the use of ART and prophylaxis however still one of the leading OI in HIV pts
  • Rare cause in HIV when CD4 >200 and when bactrim ppx is taken appropriately
  • Clinical sx: Gradual onset of fever (80-100%), cough (90%) and dyspnea (95%)
  • Diagnosis: Low CD4 (95% of cases below 200), elevated LDH in 90% of patients, often hypoxic as dz progresses, CXR normal in ¼ patients or may show diffuse, bilateral, interstitial or alveolar infiltrates
  • Treatment: TMP-SMX preferred medication, if unable to take TMP-SMX then mild/mod can be tx with atovaquone or clinda/primaquine however if severe, tx with IV pentamadine
  • Steroids are recommended for PaO2 <70, AA gradient >35 or hypoxemia on pulse ox