Pneumocystis jirovecii pneumonia

Background

• Pneumocystis (carinii) jiroveci
• Most common opportunistic infection in AIDS pts
• Most common identifiable cause of death
• Risk factors:
  • CD4 < 200
  • Immunosuppressive medications
  • Cancer
  • Primary immunodeficiencies
  • Severe malnutrition

Clinical Features

• Fever (62%)
• Dry cough
• Shortness of breath (progressive from exertion only to at rest)

Diagnosis

• Imaging
  • CXR
    • Normal in 25% of cases
    • Diffuse, interstitial infiltrates
  • CT Chest
    • Sn 100%, Sp 89%
    • May see ground glass infiltrative pattern
• Labs
  • LDH
    • Low Sn, Sp
  • ABG
    • Hypoxemia, increased A-a gradient

Work-Up

• CBC
• Chemistry
• LDH
• ABG
• CD4 count
• CXR - bat wing appearance (bilat interstitial infiltrates)
• A-a gradient
  • P(A-a)O2 = 145 – PaCO2 – PaO2 (normal is <10 in young, healthy pts)

DDX

• Dyspnea (SOB)

Treatment

Antibiotics

Mild Disease

• TMP/SMX 2 DS tablets PO q8hrs daily OR
  • High incidence of allergy in HIV
• Dapsone 100mg PO once daily + TMP 5mg/kg PO q8hrs OR
  • caution: dapsone can cause methemoglobinemia
• Atavaquone 750mg PO q12hrs OR
• Primaquine 30mg PO q24hrs + Clindamycin 450mg PO q8hrs

Severe Disease

• TMP/SMX 5mg/kg IV q8hrs daily x 21 days OR
• Pentamidine 4mg/kg IV daily infused over 60 minutes OR
  • Watch for side effects of hypoglycemia and hypotension
• Primaquine 30mg PO once daily + Clindamycin 900mg IV q8hrs daily

Prophylaxis

• TMP/SMX 1 double strength tablet daily, but one single strength tablet daily or one double-strength three times weekly is acceptable.

Disposition

• Symptoms usually worsen 2-3d after start of treatment
• Pts w/ disease severe enough to warrant IV therapy or steroids should be admitted