Lung abscess

Last updated: September 11, 2023

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Summarytoggle arrow icon

A lung abscess is a collection of pus within the lung parenchyma. While aspiration of oropharyngeal secretions is the most common cause, lung abscesses can also occur secondary to bronchial obstruction (e.g., malignancy, foreign body aspiration), hematogenous spread (e.g., infectious endocarditis, IV drug use), contiguous spread (e.g., liver abscess), and as a complication of necrotizing pneumonia. The most common causative pathogens are anaerobic bacteria, although aerobic bacteria and, in rare cases, fungi and parasites can also cause lung abscesses. Typical symptoms of a pyogenic lung abscess include fever and cough with production of foul-smelling sputum; they may take weeks or months to develop and may initially be attributed to pneumonia or pulmonary tuberculosis. Lung abscesses typically appear as spherical intraparenchymal cavitary lesions with an air-fluid level on chest imaging. Chest CT is useful for detecting smaller abscesses as well as differentiating abscesses from other cavitary pulmonary lesions. Empiric antibiotic therapy for pyogenic lung abscesses should be started immediately after obtaining relevant cultures and continued for several weeks. Occasionally, percutaneous or bronchoscopic drainage or surgical resection is required. The underlying cause should be evaluated for and treated in all patients.

Definitiontoggle arrow icon

Reference: [2]

Etiologytoggle arrow icon

Causative pathogens [2][3][4]

One of the most severe complications of influenza in children and adults is a secondary bacterial infection with Staphylococcus aureus.

Risk factors for lung abscess [2][3][4]

Pathophysiologytoggle arrow icon

Clinical featurestoggle arrow icon


Typically indolent; symptoms can evolve over weeks to months, but may also be acute in onset.

  • Acute: symptoms present for < 4–6 weeks
  • Chronic: symptoms present for > 6 weeks

Characteristic symptoms

Pulmonary examination findings

Reference: [2][3]

Diagnosticstoggle arrow icon

General principles [4]

Imaging [2][3]


  • Chest x-ray: typically the initial investigation in any suspected lung pathology
  • CT chest with IV contrast: to confirm the diagnosis and rule out differential diagnoses of lung abscesses [3]


  • Common findings on x-ray and CT
    • Spherical intraparenchymal cavity with thick irregular walls
    • Air-fluid level within the cavity that is dependent on body position
  • Additional findings on CT
  • Location of abscess
    • Due to aspiration: typically unilateral [7]
    • Due to hematogenous dissemination: typically bilateral and multiple [8]

Laboratory studies [2][4]


Additional testing (as needed)

Do not wait for culture results to start antibiotics. Start empirical treatment immediately after obtaining samples for culture, and tailor therapy as needed once culture results are available.

Diagnostics for the underlying cause

Differential diagnosestoggle arrow icon

As lung abscesses due to aspiration appear in characteristic locations, imaging can help to differentiate them from other cavitary lesions. For example, tuberculosis more commonly affects the lung apices or apical segments of the lower lobes; embolic pulmonary infarcts typically appear as multiple, diffuse lesions. [9]

References: [2][4]

The differential diagnoses listed here are not exhaustive.

Treatmenttoggle arrow icon


  • Admit the patient and start immediate empiric antibiotic therapy (after obtaining samples for culture).
  • Consider the following consults as appropriate:
    • Pulmonary
    • Infectious disease
    • Cardiothoracic surgery or interventional radiology for patients with large abscesses
    • Speech and language pathology for patients with dysphagia
  • Identify and treat the underlying cause.

Antimicrobial therapy [4][10][11]

Antimicrobial therapy should be tailored to local sensitivities. Follow local guidelines and infectious diseases advice, if available.

Suspected bacterial infection

Bacterial infection is the most common cause of lung abscess and empiric antibiotic therapy should be initiated in all patients with typical clinical features (e.g., fever, purulent sputum) and a cavitary lesion on imaging.

Empiric antibiotic therapy for bacterial lung abscess [4][10][11]
No risk factors for MRSA infection
Suspected MRSA infection

Lung abscesses due to aspiration are typically caused by anaerobic bacteria. Lung abscesses due to hematogenous spread from IV drug use are typically caused by Staphylococcus aureus and streptococci. [8]

Lung abscesses following a recent influenza infection are likely caused by Staphylococcus aureus in children and adults, but can also be caused by Streptococcus pneumoniae and Hemophilus influenzae.

Parasitic or fungal infection [13][14][15]

Suspect parasitic or fungal infection in patients with atypical clinical features (e.g., nonpurulent sputum), an inadequate response to empiric antibiotic therapy, and risk factors (e.g., immunocompromise)

Interventional therapy [2][3][4]

Management of the underlying cause

Examples include:

Complicationstoggle arrow icon

References: [2][4][16]

We list the most important complications. The selection is not exhaustive.

Acute management checklist for lung abscesstoggle arrow icon

Referencestoggle arrow icon

  1. $Contributor Disclosures - Lung abscess. None of the individuals in control of the content for this article reported relevant financial relationships with ineligible companies. For details, please review our full conflict of interest (COI) policy:.
  2. Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2). McGraw-Hill Education / Medical ; 2018
  3. Bennett JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Elsevier Health Sciences ; 2014
  4. Yazbeck MF, Dahdel M, Kalra A, Browne AS, Pratter MR. Lung Abscess: Update on Microbiology and Management. Am J Ther. 2014; 21 (3): p.217-221.doi: 10.1097/mjt.0b013e3182383c9b . | Open in Read by QxMD
  5. Wright WF, DO WF, MPH WF. Essentials of Clinical Infectious Diseases. Demos Medical Publishing ; 2013
  6. Flynn JA, Choi MJ, Wooster LD. Oxford American Handbook of Clinical Medicine. Oxford University Press ; 2013
  7. Moreira Jda S, Camargo Jde J, et al.. Lung abscess: Analysis of 252 consecutive cases diagnosed between 1968 and 2004.. J Bras Pneumol. 2006; 32 (2): p.136-43.doi: 10.1590/s1806-37132006000200009 . | Open in Read by QxMD
  8. Maitre T, Ok V, Calin R, et al. Pyogenic lung abscess in an infectious disease unit: a 20-year retrospective study. Therapeutic Advances in Respiratory Disease. 2021; 15: p.175346662110030.doi: 10.1177/17534666211003012 . | Open in Read by QxMD
  9. Kuhajda I, Zarogoulidis K, Tsirgogianni K, et al. Lung abscess-etiology, diagnostic and treatment options.. Ann Transl Med. 2015; 3 (13): p.183.doi: 10.3978/j.issn.2305-5839.2015.07.08 . | Open in Read by QxMD
  10. Gilbert, DN; Chambers, HF. Sanford Guide to Antimicrobial Therapy 2020. Antimicrobial Therapy, Inc ; 2020
  11. Rybak MJ, Lomaestro BM, Rotschafer JC, et al. Vancomycin Therapeutic Guidelines: A Summary of Consensus Recommendations from the Infectious Diseases Society of America, the American Society of Health‐System Pharmacists, and the Society of Infectious Diseases Pharmacists. Clin Infect Dis. 2009; 49 (3): p.325-327.doi: 10.1086/600877 . | Open in Read by QxMD
  12. Limper AH, Knox KS, Sarosi GA et al. An official American Thoracic Society statement: treatment of fungal infections in adult pulmonary and critical care patients. Am J Respir Crit Care Med. 2011; 183 (1): p.96-128.doi: 10.1164/rccm.2008-740ST . | Open in Read by QxMD
  13. Jindal S, Shankar PS. Handbook of Pulmonary and Critical Care Medicine. JP Medical Ltd ; 2012
  14. Magill AJ, Strickland GT, Maguire JH, Ryan ET, Solomon T. Hunter's Tropical Medicine and Emerging Infectious Disease E-Book. Elsevier Health Sciences ; 2012
  15. Ong CW, Elkington PT, Friedland JS. Tuberculosis, pulmonary cavitation, and matrix metalloproteinases. Am J Respir Crit Care Med. 2014; 190 (1): p.9-18.doi: 10.1164/rccm.201311-2106PP . | Open in Read by QxMD
  16. Walls R, Hockberger R, Gausche-Hill M. Rosen's Emergency Medicine. Elsevier Health Sciences ; 2018
  17. Ferri FF. Ferri's Clinical Advisor 2018 E-Book: 5 Books in 1 (Ferri's Medical Solutions). Elsevier ; 2017: p. 1779
  18. Davey P. Medicine at a Glance. John Wiley & Sons ; 2010
  19. Baum S, Pentecost MJ. Abrams' Angiography. Lippincott Williams & Wilkins ; 2006

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