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Synonyms: pyogenic lung infection/pneumonia, necrotising pneumonia
Severe, localised suppurative infection in the substance of the lung, associated with necrotic cavity formation. The process is usually surrounded by a fibrous reaction, forming the abscess wall. Multiple small abscess formations may occur - sometimes referred to as necrotising pneumonia.
The most frequent cause is aspiration of anaerobic organisms from the mouth in those predisposed to aspiration pneumonia, with immunodeficiency and cough reflex. A pneumonitis develops which progresses to abscess formation over a period of days or weeks.
- Inhalation of a foreign body.
- Bacteraemia seeding in the lungs.
- Tricuspid endocarditis leading to septic pulmonary embolus.
- Extension of hepatic abscess.
- Association with lung cancer.
- Proximal to bronchial obstruction.
- Complication of severe or incompletely treated pneumonia (particularly staphylococci or klebsiellae).
- Penetrating pulmonary trauma - eg, a stab wound.
NB: lung abscesses may present acutely or more chronically.
Types of lung abscesses
- Primary abscess - occurs in previously normal lungs and may follow aspiration.
- Secondary abscess - occurs in patients with an underlying lung abnormality.
Common pathogens causing lung abscess include anaerobes, Staphylococcus aureus and enteric Gram-negative rods like Klebsiella pneumoniae.
- Peptostreptococcus spp.
- Bacteroides spp.
- Fusobacterium spp.
- Microaerophilic streptococci
- S. aureus.
- Streptococcus pyogenes.
- Haemophilus influenzae.
- Pseudomonas aeruginosa.
- K. pneumoniae - becoming more prevalent.
- Burkholderia cepacia - particularly associated with cystic fibrosis.
- Streptococcus pneumoniae.
- Legionella pneumonia.
- Actinomyces spp.
- Nocardia spp.
- Proteus mirabilis.
- Pasteurella multocida - zoonotic infection from cats/dogs/cattle.
- Burkholderia pseudomallei - a soil-borne Gram-negative infection which causes a condition called melioidosis. It affects animals and humans, especially in Southeast Asia and northern Australia.
- Mycobacterial infections - predominantly tuberculosis (TB).
- Fungal lung infections, such as Aspergillus, Cryptococcus, Histoplasma, Blastomyces, Coccidioides species.
- Parasites, such as Entamoeba histolytica, Paragonimus spp.
Incidence and prevalence figures have not been established.
- Alcoholism or drug misuse.
- Following general anaesthesia.
- Diabetes mellitus.
- Severe periodontal disease.
- Stroke/cerebral palsy/cognitive impairment/impaired consciousness leading to increased risk of aspiration.
- Immunosuppression, particularly chronic granulomatous disease in children.
- Congenital heart disease.
- Chronic lung disease, particularly cystic fibrosis.
- Onset of symptoms is often insidious (more acute if following pneumonia).
- Spiking temperature with rigors and night sweats.
- Cough ± phlegm production (frequently foul-tasting and foul-smelling and often blood-stained).
- Pleuritic chest pain.
- Finger clubbing in chronic cases.
- High temperature.
- Localised dullness to percussion (if consolidation is also present or effusion).
- Bronchial breathing and/or crepitations (if consolidation is present).
- Also look for signs of severe periodontal disease and infective endocarditis.
- Other causes of chest infection or pneumonia - eg, TB and opportunistic mycobacteria.
- Neoplasia - eg, cavitating bronchial carcinoma.
- Pulmonary infarction or pulmonary embolism.
- Vasculitis - eg, granulomatosis with polyangiitis (Wegener's granulomatosis).
- Sarcoidosis with cavities.
- Infected bronchogenic cyst.
- FBC - normocytic anaemia or neutrophilia..
- Renal function.
- Blood cultures and sputum cultures (including AAFB).
- ESR/CRP usually elevated.
- CXR - shows walled cavity, usually with a fluid level; may also be presence of an empyema or effusion.
- Tapping or draining of fluid or empyema with microbiology and cytology of samples.
- CT scan of the thorax - may detect multiple small abscesses.
- Fibre-optic bronchoscopy can exclude obstruction and provide samples for culture.
- Trans-thoracic biopsy/aspiration (usually with ultrasound guidance) or trans-tracheal biopsy.
- Oxygen if required.
- Rehydration if indicated.
- Postural drainage with chest physiotherapy.
Most lung abscesses (80-90%) are now successfully treated with antibiotics.
- Begin with intravenous treatment, usually for about 2-3 weeks, and follow with oral antibiotics for a further 4-8 weeks.
- Recommended first-line therapy includes beta-lactam/beta-lactamase inhibitor or cephalosporin (second- or third-generation) plus clindamycin.
- 15-20% of anaerobic bacteria are resistant to penicillin only, so a combination of penicillin and clavulanate or a combination of penicillin and metronidazole should be considered as alternatives.
- Regimen should be altered once the organism is known.
- If the condition fails to resolve with conservative measures, drainage via a bronchoscope, CT-guided percutaneous drainage or cardiothoracic surgical intervention may be required.
- Surgery is associated with a number of complications, such as empyema and bronchoalveolar air leak - especially so in children[11, 12].
Where slow resolution occurs, the possibility of malignancy or unusual organisms must be considered.
- Bronchopleural fistula.
- Distant complications from haematogenous spread (eg, brain abscess).
- There is an overall 90% cure rate with antibiotic therapy.
- Morbidity and mortality are more likely to be associated with underlying pathology such as bronchial carcinoma.
- Prognosis is adversely affected by older age and multiple comorbidities.
- Other poor prognostic factors include pneumonia, reduced level of consciousness, anaemia and infection with P. aeruginosa, S. aureus and K. pneumoniae.
Further reading and references
; Clinical, Radiological and Bacteriological Profile of Lung Abscess - An Observational Hospital Based Study. Open Access Maced J Med Sci. 2018 Sep 236(9):1642-1646. doi: 10.3889/oamjms.2018.374. eCollection 2018 Sep 25.
; Long-term sequelae after lung abscess in children - Two tertiary centers' experience. J Infect Chemother. 2018 May24(5):376-382. doi: 10.1016/j.jiac.2017.12.020. Epub 2018 Feb 15.
; Clinical management and outcome of childhood lung abscess: a 16-year experience. J Microbiol Immunol Infect. 2005 Jun38(3):183-8.
; Lung abscess-etiology, diagnostic and treatment options. Ann Transl Med. 2015 Aug3(13):183. doi: 10.3978/j.issn.2305-5839.2015.07.08.
; Lung Abscess Remains a Life-Threatening Condition in Pediatrics - A Case Report. J Crit Care Med (Targu Mures). 2017 Aug 193(3):123-127. doi: 10.1515/jccm-2017-0023. eCollection 2017 Jul.
; An unusual case of lung abscess secondary to round pneumonia caused by recurrent Klebsiella pneumoniae strain and the role of occult metastases tumor. Respir Med Case Rep. 2018 Feb 323:107-109. doi: 10.1016/j.rmcr.2018.01.008. eCollection 2018.
; Lung abscess caused by Legionella species: implication of the immune status of hosts. Intern Med. 200948(23):1997-2002. Epub 2009 Dec 1.
; Pasteurella species. Infectious Diseases Advisor, 2018.
; Centers for Disease Control and Prevention, 2018
; A Community-acquired Lung Abscess Attributable to Streptococcus pneumoniae which Extended Directly into the Chest Wall. Intern Med. 201756(1):109-113. doi: 10.2169/internalmedicine.56.7398. Epub 2017 Jan 1.
; Clinical presentation and management of empyema, lung abscess and pleural effusion. Curr Opin Pulm Med. 2006 May12(3):205-11.
; A case of lung abscess successfully treated by transbronchial drainage using a guide sheath. Respirol Case Rep. 2017 Mar 245(3):e00228. doi: 10.1002/rcr2.228. eCollection 2017 May.
; An update on the drainage of pyogenic lung abscesses. Ann Thorac Med. 2012 Jan7(1):3-7. doi: 10.4103/1817-1737.91552.
; A 10-year retrospective review of pediatric lung abscesses from a single center. Ann Thorac Med. 2016 Jul-Sep11(3):191-6. doi: 10.4103/1817-1737.185763.
; Lung abscess predicts the surgical outcome in patients with pleural empyema. J Cardiothorac Surg. 2010 Oct 205:88. doi: 10.1186/1749-8090-5-88.
; Lung abscess and thoracic empyema: retrospective analysis in an internal medicine department. Acta Med Port. 2011 Dec24 Suppl 2:229-40. Epub 2011 Dec 31.
; Lung abscess in children. Paediatr Respir Rev. 2007 Mar8(1):77-84. Epub 2007 Feb 14.