Lung abscess overview

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Aditya Ganti M.B.B.S. [2]

Overview

Lung abscess is necrosis of the pulmonary tissue and formation of cavities (more than 2 cm) containing necrotic debris or fluid caused by microbial infection. This pus-filled cavity is often caused by aspiration, which may occur during altered consciousness. Alcoholism is the most common condition predisposing to lung abscesses. Lung abscess is considered primary (60%) when it results from existing lung parenchymal process and is termed secondary when it is complicated by another process e.g. vascular emboli or follows rupture of extrapulmonary abscess into the lung.[1]

Historical Perspective

Lung abscess has been a disease entity since the days of Hippocrates. Postural physiotherapy had been the mainstay of treatment until Harold Neuhof described his concept of new one-stage open drainage for the acute abscess in 1930's. With the invention of antibiotics in late 1940's and their promising results led the change in management of lung abscess.[2]

Pathophysiology

Aspiration of bacteria is the inciting event for the development of lung abscess. Once the aspirate is localized it results in pneumonitis. Inflammatory mediators are released, resulting in the formation of colliquative necrosis. The right side lung is more commonly affected than the left. On gross morphology, the lesions are well circumscribed filled with necrotic debris and do not demonstrate well-defined borders with the surrounding lung parenchyma. Microscopic examination demonstrates neutrophils with dilated blood vessels and inflammatory edema.[3] [4]

Causes

Lung abscess is commonly caused by bacterial infections and these include bacteroides, peptostreptococcus and prevotella.[5]Lung abscess is commonly caused by bacterial infections and these include bacteroides, peptostreptococcus and prevotella. Most of the lung abscess is caused by polymicrobial organisms of which anaerobes play a crucial role . Less common include nocardia, actinomyces and fungi. If left untreated, life-threatening conditions may develop which may result in death or permanent disability within 24 hours .

Differentiating Lung Abscess from other Diseases

Lung abscess must be differentiated from other lesions that present with similar symptoms such as cough, fever with chills and rigor and chest includes malignancy, tuberculosis, Wegener's granulomatosis, rheumatoid nodules.[6]

Epidemiology and Demographics

The incidence from lung abscess have greatly declined during the past several decades due to the widespread use of antibiotics and the availability of other treatment options. Lung abscess accounts for up to 4.0 to 5.5 per 10,000 hospital admissions each year in the US.[7]

Risk Factors

Factors resulting in the altered level of consciousness and decreased immune response play a key role in the development of lung abscess includes alcoholism, diabetes mellitus, neurological disorder and bronchial obstruction.[8]

Screening

There is no screening recommendations for lung abscess.

Natural history, Complications and Prognosis

Symptoms of lung abscess begin approximately 10 days after aspiration of infected material. Acute symptoms include a prodrome accompanied by fever, productive cough, pleuritic chest pain and occasional episodes of hemoptysis. Patients with chronic lung abscess develop weight loss and malaise.Without treatment based on the immune status of the patient, lung abscess can either resolve by forming a granulation tissue scar, or progressively worsens and can result in septicemia, hemorrhage, and death.The prognosis of lung abscess is good with appropriate antibiotic treatment with a high success rate. The outcomes depend on the other associated conditions underlying lung abscess such as size of the cavity, age of the patient and other underlying lung diseases. Complications include hemorrhage pyopneumothorax, pleural empyema and sepsis.[9][10]

Diagnosis

History and Symptoms

Patient history is important to establish a diagnosis of lung abscess. Common history findings include conditions associated with a risk of gastric content aspiration, a recent history of hospitalization or surgery. Common symptoms include high fever (>101°F [>38.5°C]), productive cough with purulent sputum, and pleuritic chest pain. Anaerobic bacteria is responsible for purulent sputum in acute lung abscess.

Physical Examination

Patients with acute lung abscess may present with fever, cough with purulent sputum, gag reflex may be absent in patients with an underlying neurological disorder such as stroke. Digital clubbing is present in patients with a chronic abscess.On examination of the chest, there will be features of consolidation. Abscess typically localizes in the upper lobes or apical segments of the lower lobes.[10]

Laboratory Findings

Diagnosis of lung abscess is made based on clinical symptoms, physical examination, radiographic studies and bacterial culture. Laboratory findings include increased acute phase reactants (ESR and CRP) levels and leukocytosis with consolidation being evident in a segmental or lobar distribution with central cavitation an air-fluid level on lung x-ray. Blood cultures should be performed in all suspected cases.

Treatment

Medical Therapy

The mainstay of management for lung abscess is hospital admission for chest drain and systemic antibiotics. Antimicrobial therapy is based on predisposing host factors and local resistance patterns.Empiric treatment should be commenced after culture samples are obtained. The regimens should penetrate the lung parenchyma and target both anaerobes, aerobic and microaerophilic streptococci. Any combination of a beta-lactam–beta-lactamase inhibitor or a carbapenem are reasonable to use. The standard duration of the treatment of lung abscess is ≥ 4–6 weeks of parenteral antibiotics. [11]

Surgical Therapy

Surgery is considered as the last resort of therapy when both medical and chest drain failed to resolve symptoms. Options for surgery includes chest tube drainage and surgical resection of the lung abscess with the surrounding lung tissue.Percutaneous and endoscopic drainage techniques are considered as a first-line management, especially for patients who are not candidates for surgery. Percutaneous drainage of lung abscesses is characterized by high therapeutic effectiveness and preservation of functional lung tissue, it is a minimally invasive method with fewer complications and lower mortality rates (approximately 4%) in comparison to surgical management. Surgical resection is considered in about 10% of the patients when the chest drain has failed to improve symptoms and patients presenting with one of the following conditions. The surgical approach is thoracotomy and the extent of surgical resection depends on the size of the underlying lesion.[12]

Reference

  1. Bartlett JG, Finegold SM (1972). "Anaerobic pleuropulmonary infections". Medicine (Baltimore). 51 (6): 413–50. PMID 4564416.
  2. Neuhof H, Hurwitt E (1943). "ACUTE PUTRID ABSCESS OF THE LUNG : VII. RELATIONSHIP OF THE TECHNIC OF THE ONE-STAGE OPERATION TO RESULTS". Ann. Surg. 118 (4): 656–64. PMC 1617784. PMID 17858299.
  3. "Lung abscess". West. J. Med. 124 (6): 476–82. 1976. PMC 1130102. PMID 936601.
  4. Green LH, Green GM (1968). "Differential suppression of pulmonary antibacterial activity as the mechanism of selection of a pathogen in mixed bacterial infection of the lung". Am. Rev. Respir. Dis. 98 (5): 819–24. doi:10.1164/arrd.1968.98.5.819. PMID 5683476.
  5. Cesar L, Gonzalez C, Calia FM (1975). "Bacteriologic flora of aspiration-induced pulmonary infections". Arch. Intern. Med. 135 (5): 711–4. PMID 28705.
  6. Chaudhuri MR (1973). "Primary pulmonary cavitating carcinomas". Thorax. 28 (3): 354–66. PMC 470041. PMID 4353362.
  7. Bartlett JG, Finegold SM (1974). "Anaerobic infections of the lung and pleural space". Am. Rev. Respir. Dis. 110 (1): 56–77. doi:10.1164/arrd.1974.110.1.56. PMID 4834618.
  8. Hagan JL, Hardy JD (1983). "Lung abscess revisited. A survey of 184 cases". Ann. Surg. 197 (6): 755–62. PMC 1352910. PMID 6859981.
  9. Adebonojo SA, Osinowo O, Adebo O (1979). "Lung abscess: a review of three years' experience at the University College Hospital, Ibadan". J Natl Med Assoc. 71 (1): 39–43. PMC 2537236. PMID 423274.
  10. 10.0 10.1 Hirshberg B, Sklair-Levi M, Nir-Paz R, Ben-Sira L, Krivoruk V, Kramer MR (1999). "Factors predicting mortality of patients with lung abscess". Chest. 115 (3): 746–50. PMID 10084487.
  11. Allewelt M, Schüler P, Bölcskei PL, Mauch H, Lode H (2004). "Ampicillin + sulbactam vs clindamycin +/- cephalosporin for the treatment of aspiration pneumonia and primary lung abscess". Clin. Microbiol. Infect. 10 (2): 163–70. PMID 14759242.
  12. Kelogrigoris, M; Tsagouli, P; Stathopoulos, K; Tsagaridou, I; Thanos, L (2011). "Ct-guided percutaneous drainage of lung abscesses: review of 40 cases". Journal of the Belgian Society of Radiology. 94 (4): 191. doi:10.5334/jbr-btr.583. ISSN 1780-2393.

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