Pulmonary Abscess

Published on 22/03/2015 by admin

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Last modified 22/03/2015

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Chapter 394 Pulmonary Abscess

Pulmonary abscesses are localized areas composed of thick-walled purulent material formed as a result of lung infection that lead to destruction of lung parenchyma, cavitation, and central necrosis. Lung abscesses are much less common in children than in adults. A primary lung abscess occurs in a previously healthy patient with no underlying medical disorders. A secondary lung abscess occurs in a patient with underlying or predisposing conditions.

Pathology and Pathogenesis

A number of conditions predispose children to the development of pulmonary abscesses, including aspiration, pneumonia, cystic fibrosis (Chapter 395), gastroesophageal reflux (Chapter 315.1), tracheoesophageal fistula (Chapter 311), immunodeficiencies, postoperative complications of tonsillectomy and adenoidectomy, seizures, and a variety of neurologic diseases. In children, aspiration of infected materials or a foreign body is the predominant source of the organisms causing abscesses. Initially, pneumonitis impairs drainage of fluid or the aspirated material. Inflammatory vascular obstruction occurs, leading to tissue necrosis, liquefaction, and abscess formation. Abscess can also occur as a result of pneumonia and hematogenous seeding from another site.

If the aspiration event occurred while the child was recumbent, the right and left upper lobes and apical segment of the right lower lobes are the dependent areas most likely to be affected. In a child who was upright, the posterior segments of the upper lobes were dependent and therefore are most likely to be affected. Primary abscesses are found most often on the right side, whereas secondary lung abscesses, particularly in immunocompromised patients, have a predilection for the left side.

Both anaerobic and aerobic organisms can cause lung abscesses. Common anaerobic bacteria that can cause a pulmonary abscess include Bacteroides spp, Fusobacterium spp, and Peptostreptococcus spp. Abscesses can be caused by aerobic organisms such as Streptococcus spp, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Aerobic and anaerobic cultures should be part of the work-up for all patients with lung abscess. Occasionally, concomitant viral-bacterial infection can be detected. Fungi can also cause lung abscesses, particularly in immunocompromised patients.

Diagnosis

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