Internal Medicine · Year 3 · from Internal Medicine

Case 3: Aspiration Pneumonia

Patient Presentation

A 78-year-old man with a history of Parkinson's disease and prior stroke with residual dysphagia presents from a skilled nursing facility with fever, cough, and respiratory distress. Staff reports he had a witnessed choking episode 2 days ago during lunch. He has been coughing and short of breath since then with foul-smelling sputum.

Vital Signs

  • Blood Pressure: 95/58 mmHg
  • Heart Rate: 112 bpm
  • Respiratory Rate: 28/min
  • Oxygen Saturation: 85% on room air
  • Temperature: 39.4°C

Physical Examination

  • General: Ill-appearing, moderate respiratory distress
  • HEENT: Poor dentition, unable to follow commands consistently
  • Pulmonary: Decreased breath sounds right base, crackles bilaterally
  • Cardiovascular: Tachycardic
  • Neurologic: Resting tremor, rigidity, delayed responses

Laboratory and Imaging

  • WBC: 22,400/μL with left shift
  • Lactate: 3.2 mmol/L
  • Chest X-ray: Right lower lobe infiltrate with air-fluid level suggesting abscess
  • CT Chest: Right lower lobe consolidation with cavity and air-fluid level

Clinical Image

Figure 3: CT scan of the chest showing a lung abscess with air-fluid level in the right lower lobe, a common complication of aspiration pneumonia.

Image Source: Educational illustration for teaching purposes.

Questions

  1. What anatomic factors explain why aspiration pneumonia commonly affects the right lower lobe?
  • A) Right lower lobe has poorest blood supply
  • B) Right main bronchus is more vertical and wider; dependent segments affected
  • C) Right lower lobe is largest
  • D) Random distribution
  1. What pathogens are commonly involved in aspiration pneumonia?
  • A) Streptococcus pneumoniae alone
  • B) Anaerobes (from oral flora), plus gram-negatives and gram-positives
  • C) Only aerobic bacteria
  • D) Primarily viral
  1. What antibiotic regimen is appropriate for aspiration pneumonia with suspected lung abscess?
  • A) Azithromycin alone
  • B) Ampicillin-sulbactam or piperacillin-tazobactam or clindamycin + fluoroquinolone
  • C) Ceftriaxone alone
  • D) Vancomycin alone
  1. What is the difference between aspiration pneumonitis and aspiration pneumonia?
  1. What interventions can reduce aspiration risk in this patient?

Answers

  1. B) Right main bronchus is more vertical and wider; dependent segments affected - The right main bronchus takes off at a less acute angle than the left, and gravity directs aspirated material to dependent segments. When supine: posterior segments of upper lobes and superior segments of lower lobes. When upright: basal segments of lower lobes (more common on right).
  1. B) Anaerobes (from oral flora), plus gram-negatives and gram-positives - Aspiration introduces oral flora:
  • Anaerobes: Peptostreptococcus, Fusobacterium, Prevotella, Bacteroides
  • Gram-positives: Streptococci
  • Gram-negatives: Enteric bacteria (especially in nursing home patients)
  • Polymicrobial infection is common
  1. B) Ampicillin-sulbactam or piperacillin-tazobactam or clindamycin + fluoroquinolone - Coverage should include anaerobes:
  • Ampicillin-sulbactam 3g IV q6h
  • Piperacillin-tazobactam 4.5g IV q6h
  • Alternative: Clindamycin + fluoroquinolone or ceftriaxone
  • Metronidazole alone has poor activity against microaerophilic streptococci
  1. Aspiration pneumonitis vs. aspiration pneumonia:
  • Pneumonitis: Chemical injury from gastric acid; acute onset; often resolves without antibiotics; may progress to ARDS
  • Pneumonia: Bacterial infection from aspirated oral/gastric contents; develops over hours to days; requires antibiotics
  • Clinical distinction: Pneumonitis presents immediately; pneumonia develops over 24-72 hours
  • If unclear, treat as infection; if witnessed aspiration with rapid improvement, may withhold antibiotics
  1. Aspiration prevention strategies:
  • Speech therapy evaluation for dysphagia
  • Modified diet texture (thickened liquids, pureed foods)
  • Upright positioning during and after meals (30-45 minutes)
  • Supervised feeding
  • Oral hygiene to reduce bacterial load
  • Consider PEG tube if severe dysphagia (though does not eliminate aspiration risk)
  • Optimize treatment of underlying conditions (Parkinson's, stroke)

Learning Points

  1. CURB-65 and PSI help determine site of care for CAP; low scores may allow outpatient treatment.
  1. Empiric CAP treatment should cover typical (S. pneumoniae) and atypical (Mycoplasma, Legionella) pathogens.
  1. HAP and VAP require broader coverage including Pseudomonas and MRSA based on local resistance patterns and patient risk factors.
  1. Aspiration pneumonia often involves anaerobes and polymicrobial infection; antibiotic coverage should include anaerobic activity.
  1. De-escalation of antibiotics based on culture results and clinical response is important for antibiotic stewardship.

All cases for this lecture as Markdown