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Pneumocystis Pneumonia (PCP / PJP)

Pneumonia

Source: IDMP View antifungal coverage →
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Patient
Clinical scenario / source

Annotations only — chart still shows the full chemistry of each drug.

1. Clinical Syndrome

Subacute progressive pneumonia in immunocompromised hosts caused by Pneumocystis jirovecii. Hallmark presentation: weeks of progressive dyspnea, dry cough, hypoxia disproportionate to imaging, bilateral interstitial / ground-glass infiltrates with upper-lobe predominance (in HIV) or diffuse (in non-HIV). LDH elevated, 1,3-β-D-glucan elevated, BAL DFA / PCR diagnostic.

2. Pathogens

Consider the patient: HIV with CD4 <200 (esp. <100), oral thrush; chronic steroids ≥20 mg prednisone × ≥4 weeks; biologics (rituximab, alemtuzumab); solid organ transplant; HSCT; hematologic malignancy on high-dose chemo; idiopathic CD4 lymphopenia; congenital immunodeficiency.

Consider the case: Severity is graded by oxygenation — A-a gradient and PaO2 on room air guide both regimen and adjunctive steroid use. PCR-positive does NOT always mean disease (colonization). Treat based on clinical picture + supporting diagnostics.

Common

3. Empiric Therapy

TierFirst choiceAlternativesDurationComments
Outpatient
  • 15–20 mg/kg/day TMP · divided q6–8h · PO · 21 days

    PaO2 >70 on RA, A-a <35. Outpatient appropriate if reliable, no comorbid hypoxia, can swallow.

  • 750 mg · PO BID · PO · 21 days

    MILD disease only. Take with FATTY meal — bioavailability triples. Use suspension, not tablets.

21 daysMild disease (PaO2 >70 on RA, A-a <35). 21-day total course.
Admitted to ward
  • 15–20 mg/kg/day TMP · divided q6–8h · IV · 21 days

    Switch to PO when stable + tolerating PO.

  • 600 mg · IV q6h · IV · 21 days

    Combo with primaquine 30 mg base PO daily — sulfa-allergic alternative. CHECK G6PD before primaquine.

  • 30 mg base · PO daily · PO · 21 days

    Pair with clindamycin. CHECK G6PD.

21 daysModerate disease. Add adjunctive steroids if A-a 35–45 or PaO2 60–70.
Acute / severe
  • 15–20 mg/kg/day TMP · divided q6–8h · IV · 21 days

    FIRST-LINE even in severe disease. ADD STEROIDS if A-a >35 or PaO2 <70.

  • 4 mg/kg · q24h · IV · 21 days

    TMP-SMX intolerant. Daily BMP — nephrotoxicity, hypoglycemia, pancreatitis.

  • 600 mg · IV q6h · IV · 21 days

    Combo with primaquine 30 mg base PO daily — sulfa-allergic alternative for moderate–severe disease.

  • 30 mg base · PO daily · PO · 21 days

    Pair with clindamycin. CHECK G6PD before first dose.

21 daysSevere disease (PaO2 <70 OR A-a >35) — **adjunctive steroids mandatory**: prednisone 40 mg PO BID × 5 d → 40 mg PO daily × 5 d → 20 mg PO daily × 11 d (or methylprednisolone IV equivalent if NPO). Steroids before or with first antifungal dose to blunt inflammatory response.

4. Directed Therapy

Confirm with BAL DFA / PCR (gold standard) and serum 1,3-β-D-glucan (sensitive but non-specific). Treat 21 days. Transition to secondary prophylaxis at completion (CD4 <200 in HIV; per protocol for non-HIV).

Steroid dosing for PaO2 <70 OR A-a >35:

  • Prednisone 40 mg PO BID × 5 days
  • → 40 mg PO daily × 5 days
  • → 20 mg PO daily × 11 days (total 21-day taper)
  • Or methylprednisolone IV equivalent if NPO
  • Start before or with first antifungal dose

Prophylaxis triggers (start AFTER any acute episode resolves):

  • HIV CD4 <200 OR CD4% <14% OR oral thrush
  • ≥20 mg prednisone × ≥4 weeks + other risks
  • HSCT, SOT per program protocol
  • Hematologic malignancy on high-dose chemo / fludarabine / alemtuzumab

5. Monitoring

Resolution: improvement in oxygenation 5–7 days; LDH trend.

Toxicity:

  • TMP-SMX: K (hyperkalemia); Cr (creatinine ↑ from secretion blockade — usually pseudo-AKI but check eGFR if rising); rash; LFTs; CBC weekly
  • Pentamidine: BMP daily (hypoglycemia, hypoMg, hypoCa); ECG (QTc); lipase if pancreatitis suspected
  • Clindamycin: C. diff watch
  • Primaquine + dapsone: methemoglobinemia (pulse ox falsely LOW); hemolysis (CBC, retic); CHECK G6PD first
  • Atovaquone: failure often = inadequate absorption — confirm fatty meal

Steroids: glucose, BP, sodium; taper as scheduled.

Pearls

Start empiric if high suspicion — don't wait for BAL.

STEROIDS adjunctive if PaO2 <70 OR A-a >35 — most impactful intervention after antifungal. Strong data in HIV, commonly extrapolated to non-HIV (weaker evidence).

Sulfa-intolerant alternatives by severity:

  • Mild → atovaquone (with fatty meal) or dapsone (CHECK G6PD)
  • Moderate–severe → clindamycin + primaquine (CHECK G6PD) or pentamidine

Pulse oximetry reads FALSELY LOW in dapsone/primaquine methemoglobinemia — get a co-oximetry / methemoglobin level if cyanosis with normal PaO2 (saturation gap).

Inhaled pentamidine is for prophylaxis ONLY — does not reach alveoli adequately for treatment.

HIV-specific: start ART within 2 weeks (no IRIS delay for PCP). Continue secondary prophylaxis until CD4 >200 × 3 months on suppressive ART.

Do not test asymptomatic patients — PCR can stay positive; colonization vs disease.

References