Necrosis of lung tissue due to localized area of lung infection is called a lung abscess. Such necrosis is due to thrombosis of the segmental artery and vein due to virulent infection. It is usually secondary to primary pneumonia of the lung with bacterial species that are noted for their necrotizing ability. This so called post pneumonic abscess is frequently located in the upper lobe.

Causes-

1.   Aspiration of gastric contents followed by pneumonia. Abscess which follow aspiration are usually located in the posterior lobes.

2.   Septic emboli.

3.   Pulmonary abscess may develop about a foreign material carried into the lung by a penetrating injury.

4.   Lung abscesses may be secondary to chronic upper respiratory infection, for example, dental infection, tonsillitis or a sinusitis.

5.   Partial or complete bronchial obstruction in which case infection is laid distal to the growth. The cause of obstruction is often a bronchial neoplasm or rarely bronchial stenosis from previous inflammatory disease. These are seen in patients over 40 years of age.

6.   Causative organisms- Staphylococcus aureus, Streptococcus, Pneumococcus, Haemophilus Influenzae, Coliform organisms. Anaerobic organisms which comes from dental infection.

Patient becomes ill for a few days with dry cough and pleural pain. This is the initial stage of lung abscess formation. There is expectoration of considerable quantities of offensive sputum which contains pus and blood. This occurs when the lung abscess forms communication with bronchi.

Laboratory tests to diagnose lung abscess are-

1.   Blood test.

2.   Sputum is sent for culture and sensitivity test.

3.   Chest X-ray.

4.   Bronchoscopy.

Treatment-

1.   About 80% to 90% of lung abscesses can be treated successfully with medicines. Drainage of abscess cavity is done by postural means.

2.   Failure of patient to respond to medicinal treatment is the main indication for surgical intervention. Surgical treatment is of two types-

• Pneumonotomy.
• Pulmonary resection.