Pneumocystis jirovecii

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Key Points

  • Pneumocystis jirovecii
    • Characteristics
      • Spore-producing fungus
        • originally mistakenly classified as protozoan
    • Transmission
      • Transmitted via airborne route
      • Opportunistic
        • Usually in immunocompromised patients (e.g. AIDS)
          • AIDS-defining illness
    • Presentation
      • Pneumonia
        • Also referred to as pneumocystis pneumonia (PCP)
        • Fever, dry cough, hypoxemia and shortness of breath
        • Diffuse, bilateral interstitial infiltrates seen on CXR
    • Diagnosis
      • Elevated LDH seen in HIV individuals
      • Induced sputum or bronchoalveolar lavage
        • PCR-based diagnostic studies are gold-standard
        • Fungi can be visualized/stained under microscope with fluorescent-conjugated anti-pneumocystis antibodies, calcofluor white, cresyl echt violet, methenamine silver, toluidine blue
    • Treatment/prophylaxis
      • TMP-SMX
        • Start prophylaxis when CD4+ <200 cells/mm3 in HIV patients
        • Patients allergic to TMP-SMX should be desensitized and then given TMP-SMX anyways
      • Pentamidine
        • Given IV for severe disease
      • Atovaquone, Dapsone, Clindamycin, Primaquine are all used as second line agents
        • TMP-SMX is much preferred over these drugs