Lung abscess


Lung abscess is a type of liquefactive necrosis of the lung tissue and formation of cavities more than 2 cm1 containing necrotic debris or fluid caused by microbial infection

This pus-filled cavity is often caused by aspiration, which may occur during anesthesia, sedation, or unconsciousness from injury Alcoholism is the most common condition predisposing to lung abscesses

Lung abscess is considered primary 60%2 when it results from existing lung parenchymal process and is termed secondary when it complicates another process eg vascular emboli or follows rupture of extrapulmonary abscess into lung

Contents

  • 1 Signs and symptoms
  • 2 Causes
  • 3 Diagnosis
    • 31 Imaging studies
    • 32 Laboratory studies
  • 4 Management
  • 5 Prognosis
    • 51 Complications
  • 6 See also
  • 7 References

Signs and symptomsedit

Onset of symptoms is often gradual, but in necrotizing staphylococcal or gram-negative bacillary pneumonias patients can be acutely ill Cough, fever with shivering, and night sweats are often present Cough can be productive of foul smelling purulent mucus ≈70% or less frequently with blood in one third of cases3 Affected individuals may also complain of chest pain, shortness of breath, lethargy and other features of chronic illness

Those with a lung abscess are generally cachectic at presentation Finger clubbing is present in one third of patients3 Dental decay is common especially in alcoholics and children On examination of the chest there will be features of consolidation such as localized dullness on percussion and bronchial breath sounds

Causesedit

Conditions contributing to lung abscess
  • Aspiration of oropharyngeal or gastric secretion
  • Septic emboli
  • Necrotizing pneumonia4
  • Vasculitis: Granulomatosis with polyangiitis
  • Necrotizing tumors: 8% to 18% are due to neoplasms across all age groups, higher in older people; primary squamous carcinoma of the lung is the most common
Organisms

In the post-antibiotic era pattern of frequency is changing In older studies anaerobes were found in up to 90% cases but they are much less frequent now5

  • Anaerobic bacteria: Actinomyces, Peptostreptococcus, Bacteroides, Fusobacterium species,
  • Microaerophilic streptococcus : Streptococcus milleri
  • Aerobic bacteria: Staphylococcus, Klebsiella, Haemophilus, Pseudomonas, Nocardia, Escherichia coli, Streptococcus, Mycobacteria6
  • Fungi: Candida, Aspergillus
  • Parasites: Entamoeba histolytica

Diagnosisedit

Imaging studiesedit

Lung abscesses are often on one side and single involving posterior segments of the upper lobes and the apical segments of the lower lobes as these areas are gravity dependent when lying down Presence of air-fluid levels implies rupture into the bronchial tree or rarely growth of gas forming organism

Laboratory studiesedit

Raised inflammatory markers high ESR, CRP are common but nonspecific Examination of the coughed up mucus is important in any lung infection and often reveals mixed bacterial flora Transtracheal or transbronchial via bronchoscopy aspirates can also be cultured Fiber optic bronchoscopy is often performed to exclude obstructive lesion; it also helps in bronchial drainage of pus

Managementedit

Broadspectrum antibiotic to cover mixed flora is the mainstay of treatment Pulmonary physiotherapy and postural drainage are also important Surgical procedures are required in selective patients for drainage or pulmonary resection

Prognosisedit

Most cases respond to antibiotics and prognosis is usually excellent unless there is a debilitating underlying condition Mortality from lung abscess alone is around 5% and is improving

Complicationsedit

Rare nowadays but include spread of infection to other lung segments, bronchiectasis, empyema, and bacteremia with metastatic infection such as brain abscess2

See alsoedit

  • Empyema
  • Bronchiectasis
  • Abscess
  • Pleural effusion

Referencesedit

  1. ^ Bartlett JG, Finegold SM 1972 "Anaerobic pleuropulmonary infections" Medicine Baltimore 51 6: 413–50 PMID 4564416 doi:101097/00005792-197211000-00001 
  2. ^ a b "Pneumonia and Other Pulmonary Infections: Lung Abscess, Medscape" Archived from the original on 2008-03-21 Retrieved 2007-06-20 
  3. ^ a b Moreira Jda S, Camargo Jde J, Felicetti JC, Goldenfun PR, Moreira AL, Porto Nda S 2006 "Lung abscess: analysis of 252 consecutive cases diagnosed between 1968 and 2004" Jornal brasileiro de pneumologia : publicaça̋o oficial da Sociedade Brasileira de Pneumologia e Tisilogia 32 2: 136–43 PMID 17273583 
  4. ^ Tamparo, Carol 2011 Fifth Edition: Diseases of the Human Body Philadelphia, PA: F A Davis Company p 367 ISBN 978-0-8036-2505-1 
  5. ^ Bartlett JG 2005 "The role of anaerobic bacteria in lung abscess" Clin Infect Dis 40 7: 923–5 PMID 15824980 doi:101086/428586 
  6. ^ 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 doi:101378/chest1153746 


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