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Lung Abscess

Lung Abscess is a topic covered in the 5-Minute Clinical Consult.

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  • The term lung abscess refers to a microbial infection of the lung that results in necrosis of pulmonary parenchyma typically forming a single walled-off cavity >2 cm in diameter (1).
  • Necrotizing pneumonia and lung gangrene, which are on the same clinical spectrum, are usually in multiple areas of the lung caused by a virulent pathogen.


  • In the age of antibiotics, this is a very uncommon infection, and the exact incidence is unknown.
  • Typically affects middle-aged men with predisposition to aspiration especially alcoholics (2)

Etiology and Pathophysiology

  • Most commonly, oral bacteria from the gingival crevice are aspirated which lead to inflammation and eventual liquefactive necrosis with abscess formation (2).
  • Less commonly, septic emboli from endocarditis and others
  • Because microbiologic growth is scant from sputum and invasive specimen procurement is rarely pursued, treatment is empiric.
  • Immunocompetent hosts: anaerobic bacteria and micro-aerophilic streptococci, occasionally Staphylococcus aureus especially MRSA
  • Immunocompromised: pseudomonas and gram-negative rods in addition to those mentioned above. Attention should also be paid to the possibility of atypical organisms like fungi, Nocardia, Rhodococcus, TB, and Actinomyces.
  • Rarely, amebic liver abscesses can rupture through the diaphragm and cause lung abscess; consider if there is history of prolonged stay in an endemic region.

No known genetic pattern

Risk Factors

  • Aspiration risk factors
    • Alcohol intoxication (loss of consciousness)
    • Heroin and other CNS depressant drugs
    • Seizure
    • General anesthesia with surgery
    • Dysphagia from muscular dysfunction either local or systemic
    • Tracheal/nasogastric tube and severe GERD
  • Airway obstruction
    • Neoplasia
    • External compression from lymph nodes
    • Endobronchial foreign bodies
  • Immune compromise
    • Neutropenia
    • Malignancy and chemotherapy
    • HIV infection
    • Chronic steroid use
    • Cystic fibrosis

General Prevention

  • Treatment of predisposing diseases
  • Aspiration precautions
  • Treatment of periodontal diseases

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Stephens, Mark B., et al., editors. "Lung Abscess." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816233/all/Lung_Abscess.
Lung Abscess. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816233/all/Lung_Abscess. Accessed April 26, 2019.
Lung Abscess. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816233/all/Lung_Abscess
Lung Abscess [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 26]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816233/all/Lung_Abscess.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Lung Abscess ID - 816233 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816233/all/Lung_Abscess PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -