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Pneumonia in HIV/AIDS: Why Risk Is Higher & How It's Managed

Pneumonia is a leading cause of morbidity and mortality in people with HIV, especially when CD4 count <200 cells/µL (AIDS-defining). Immunosuppression alters the pathogen spectrum, presentation, and severity.

Why HIV Increases Pneumonia Risk

  • CD4+ T-cell depletion: Impairs cell-mediated immunity (intracellular pathogens), humoral help, macrophage activation.
  • Mucosal barrier breakdown: GI/lung epithelium damage → translocation.
  • Comorbidities: Smoking (2-3x general population), IV drug use, malnutrition, structural lung disease.
  • ART Immune Reconstitution: IRIS (immune reconstitution inflammatory syndrome) can unmask/worsen pneumonia after ART start.

Pathogen Spectrum by CD4 Count

CD4 CountTypical PathogensClinical Notes
>500S. pneumoniae, H. influenzae, M. pneumoniae, viruses (flu, RSV, COVID), M. tuberculosisSimilar to immunocompetent; but ↑ severity, atypical presentation
200-500Above + P. jirovecii (PJP), M. tuberculosis, fungal (Cryptococcus, Histoplasma)PJP prophylaxis indicated <200
<200PJP (most common OI), TB, Cryptococcus, Nocardia, CMV, M. avium complex, bacterial (including P. aeruginosa)Multiple concurrent pathogens common; disseminated disease
<50All above + CMV, disseminated MAC, Cytomegalovirus, AspergillusHigh mortality; empiric broad coverage often needed

Clinical Presentation

  • Subacute/insidious (PJP, TB, fungal): Weeks of dyspnea, dry cough, fever, weight loss.
  • Acute (bacterial/viral): Days of productive cough, pleuritic pain, high fever.
  • Atypical: Minimal fever, scant sputum, normal CXR early (PJP).
  • Extrapulmonary signs: Skin lesions (Crypto, disseminated MAC), neuro symptoms (CMV, Crypto).

Diagnostic Workup

  1. CXR / CT: Diffuse interstitial (PJP), upper lobe cavitary (TB), nodules/miliary (fungal/TB), lobar consolidation (bacterial). Normal CXR ≠ no PJP.
  2. Sputum/BAL: Induced sputum (hypertonic saline) for PJP PCR (↑ sensitivity), AFB smear/culture/PCR (TB), fungal culture, bacterial culture, viral PCR panel.
  3. Blood: BCx, Crypto antigen, CMV PCR, β-D-glucan (PJP/fungal), CD4, viral load.
  4. Bronchoscopy (BAL/TBBx): If non-diagnostic sputum, severe, or need tissue.

Treatment Principles

  • Empiric Therapy: Cover likely pathogens by CD4 stratum. PJP: TMP-SMX (1st line), alternatives (dapsone+TMP, atovaquone, clindamycin+primaquine, pentamidine). TB: RIPE regimen. Fungal: Amphotericin B → azole.
  • Adjunctive Corticosteroids: For PJP with PaO₂ <70 mmHg or A-a gradient >35 mmHg (prednisone taper).
  • ART Initiation: Within 2 weeks for most OIs (except TB meningitis, cryptococcal meningitis → delay 4-6 weeks).
  • Prophylaxis: TMP-SMX DS daily (CD4<200 or prior PJP/oral thrush). Dapsone, atovaquone, aerosolized pentamidine alternatives.

Prevention

  • ART to maintain CD4 >500 (U=U).
  • Vaccines: PCV20/PPSV23, Influenza (annual), COVID, HBV, HAV, HPV.
  • TMP-SMX prophylaxis per guidelines.
  • TB screening (IGRA/TST) at entry, annually if high risk.
  • Smoking cessation — single biggest modifiable risk factor.

Pneumonia in HIV is a marker of immune deficiency. Aggressive diagnosis, pathogen-directed therapy, and early ART save lives. Prophylaxis and vaccination prevent many episodes.

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