Prerequisites and Predisposing Conditions

• Aspiration of a Large Bacterial Inoculum:
  The aspiration of oropharyngeal contents with a bacterial bolus inoculum is the prerequisite for development of lung abscess.
• Loss of Cough Reflex:
  If the cough reflex is intact, significant aspiration is not possible unless it is overwhelming. Altered sensorium is the most common state when cough reflex is suppressed, thus CVA, drug overdose, alcoholism, post-op state or coma from any cause is the most common predisposing factor for lung abscess.
• Trouble with Deglutition:
  This occurs with neurological disorders and esophageal diseases. Aspiration to lungs is frequent in this situation even if the cough reflex is intact. In many of the Esophageal diseases the mode of presentation is Lung abscess.
• Post Obstructive Pneumonia:
  Lung abscess can occur as a complication of post obstructive pneumonia as seen in some patients with lung cancer or foreign body aspiration.