Lung Abscess

Question 1

Definition of Lung Abscess

Answer 1

Localized necrosis of lung tissue with cavity formation due to microbial infection. Usually a single dominant cavity <2 cm.

Question 2

Acute vs. Chronic Lung Abscess

Answer 2

• Acute: <4-6 weeks (40% of cases)
• Chronic: >4-6 weeks

Question 3

Typical Locations (Due to Aspiration)

Answer 3

• Posterior upper lobes
• Superior lower lobes
• More common in the right lung

Question 4

Etiology – Primary Lung Abscess

Answer 4

• Anaerobes & microaerophilic streptococci
• Risk factors: Alcoholism, seizures, stroke, poor dental hygiene, aspiration risk, bulbar dysfunction

Question 5

Etiology – Secondary Lung Abscess

Answer 5

1. Post-obstructive (tumor, foreign body)
2. Immunosuppression (HIV, systemic illness)
3. Septic emboli (tricuspid endocarditis, Lemierre’s syndrome)

Question 6

Clinical Presentation

Answer 6

• Productive cough, pleuritic chest pain, fever
• Chronic: weight loss, fatigue, night sweats, anemia, foul-smelling sputum
• Acute: rapid deterioration (e.g. staph)

Question 7

Differential Diagnosis of Cavitary Lung Lesions

Answer 7

• Malignancy
• Pulmonary infarct
• GPA
• Septic emboli
• Sarcoidosis
• COP
• Cyst

Question 8

Diagnosis of Lung Abscess

Answer 8

• Chest X-ray: may show air-fluid level
• Confirmed with CT
• Microbiological workup if no response to empiric antibiotics

Question 9

Microbiological Workup (Secondary Abscess)

Answer 9

• Blood and sputum cultures
• Serology for opportunistic pathogens
• Bronchoscopy with BAL or CT-guided aspiration

Question 10

Treatment Options

Answer 10

1. Clindamycin 600 mg IV ×3/day → switch to PO 300 mg ×4/day if improving
2. Beta-lactam/beta-lactamase combo → switch to PO Augmentin if stable

Question 11

Duration of Treatment

Answer 11

• Minimum 3–4 weeks, often up to 14 weeks
• Continue until clinical and radiographic resolution

Question 12

When to Consider Drainage or Surgery

Answer 12

• No response within 7 days
• Abscess >6–8 cm
• Persistent fever and radiologic progression

Question 13

Complications

Answer 13

• Bronchiectasis
• Pneumatocele
• Recurrent abscess
• Empyema
• Life-threatening hemoptysis
• Massive aspiration of abscess contents

Question 14

Poor Prognostic Factors

Answer 14

• Age >60
• Aerobic bacteria
• Sepsis at presentation
• Symptoms >8 weeks
• Abscess size >6 cm

Question 15

Prevention of Lung Abscess

Answer 15

• Elevate head of bed, reduce sedation
• Maintain airway protection
• Oral hygiene
• Prophylaxis in high-risk patients (e.g., HIV, post-BMT)