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

• Abx
  • TMP-SMX PO or IV
    • Consider IV for:
      • Severe respiratory distress
      • A-a gradient > 45mmHg OR PaO2 < 60mmHg
    • 2 DS tabs PO TID OR 15-20mg TMP IV in divided doses q6-8hr
• Steroids - Give before TMP/SMX to blunt inflammatory reaction from bacteria death
  • Indicated for severe cases:
    • A-a gradient >35mmHg
    • PaO2 <70mmHg
  • Prednisone 40 mg PO BID x5d followed by 21d taper

Disposition

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

Source

• Uptodate
• Rosen
• Tintinalli