Infectious Disease
Pneumonia & Mycobacterial Infections
Infectious Disease

Pneumonia & Mycobacterial Infections

CAP, atypicals, aspiration, lung abscess, empyema, TB.

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◆Community-acquired pneumonia

  • •Typical: productive cough + fever + pleuritic pain + lobar infiltrate → S. pneumoniae
  • •Atypical (young + dry cough + pharyngitis + normal CXR): Mycoplasma → macrolide or doxycycline
  • •Recurrent same lobe → bronchial obstruction (tumor, FB)

◆Aspiration

  • •Aspiration pneumonia (foul sputum + dependent lobe + alcoholic/stroke/dementia): ampicillin-sulbactam or clindamycin (anaerobes)
  • •Aspiration pneumonitis (vomiting + hypoxia, no fever): supportive care only
  • •Lung abscess: cavitary + air-fluid level → anaerobic coverage 4–6 weeks
  • •Empyema: pH<7.2, glucose<60, Gram stain+, purulent → CHEST TUBE + abx (drainage essential)

◆TB

  • •PPD cutoffs: ≥5 (HIV, contacts, immunosuppressed), ≥10 (immigrants, HCW, CKD, DM, IVDU), ≥15 (low-risk)
  • •Latent: positive PPD + normal CXR → INH + B6 × 9 months (or rifapentine + INH × 12 wks)
  • •Active: hemoptysis + night sweats + apical cavitary lesions → isolate + RIPE
  • •RIPE: Rifampin, Isoniazid, Pyrazinamide, Ethambutol
  • •Confirm with sputum AFB smear + culture; NAAT for speed

◆Opportunistic infections

  • •PJP (HIV CD4<200): bilateral interstitial + hypoxia → TMP-SMX + corticosteroids (if PaO₂ <70 or A-a >35); prophylaxis when CD4<200
  • •ABPA (asthma + brown sputum + ↑IgE + central bronchiectasis): systemic steroids + itraconazole if recurrent
  • •Aspergilloma (mobile fungal ball in old cavity): observe unless severe hemoptysis

High-yield pearls

  • ◆Stroke + dysphagia: prevent aspiration with HOB elevation, swallow eval, oral hygiene
  • ◆Post-sternotomy fever + chest pain + mediastinal widening = mediastinitis → urgent surgical debridement + IV abx
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