Lung abscess definition, causes, pathology and treatment

This article is to discuss the definition , aetiology , pathogenesis , and treatment of lung abscess .

What is meant by Lung abscess ?

 A lung abscess is a localized area within the lung parenchyma that develops from an initial pneumonic stage.
The centre of the infected area first becomes necrotic and purulent .

What are the causes of lung abscess ?

Aetiology : 
(The causative organisms are Staphylococcus. aureus or S. pyogenes organism)
1- Primary (aspiration or inhalation) usually it is right and basal, the causes are :
- Loss of Consciousness
- G. anesthesia
- Gastro-esophageal reflux
- Alcohol abuse
- During vomiting

2- Secondary to :
- Lung disease : Pneumonia , Infected cyst ,  Bronchial carcinoma .
- Subdiaphragmatic : Amoebic abscess or subphrenic abscess .
- Mediastinal & thoracic wall diseases .

Pathology of primary abscess

I. Pneumonic stage.
Area of consolidation + overlying acute pleurisy

II. Stage of acute abscess .
Suppuration & pus discharge into near-by bronchus leaving cavity with irregular wall + inflamed pleura

III. Chronic abscess .
Cavity with regular & smooth border i.e the wall of abscess become intensely lined with fibrous and granulation tissue.
The pleura becomes thick.
pathology of lung abscess

Lung abscess is usually is surrounded by pneumonic consolidation .

Diagnosis of Lung abscess | symptoms, signs and investigations : Here

Treatment of lung abscess :

(The duration of antibiotic therapy is about 4-8 weeks).
1- Postural drainage
2- The antibiotic of choice is clindamycin (Dalacin-C) 600 mg/8hours I.V, then after clinical improvement and when fever subsides we give oral C1indamycin
300-450 mg every 6 hours. Clindamycin must be combined with ampicillin or amoxicillin 2gm I.V/6hours then 500mg/6hours oral .
3- Metronidazole infusion then oral 500 mg/6hours can be used instead of clindamycin.
4- Ampicillin/sulbactam (unasyn) or amoxicilline/clavulanate (augmentin) are better to be used instead of ampicillin or amoxicilline.
5- Expectorants
6- Surgery for resistant cases e.g lobectomy or segmentectomy

Suppurative pneumonia

 is a term used to describe a form of pneumonic consolidation in which there is destruction of the lung parenchyma by the inflammatory process.
Although micro abscess formation is a characteristic histological feature, it is used to restrict the term pulmonary abscess to lesions in which there is large localized collection of pus .
Lung abscess definition, causes, pathology and treatment
Dr.Tamer Mobarak


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