What is Lung Abscess

A lung abscess is a localised infection within the lung. An abscess is a pus-containing cavity. It usually occurs as a complication of inadequately treated pneumonia, when the bacteria are able to replicate to large numbers and cause damage to the lung tissue. The damaged tissue is walled off by the immune system and becomes an abscess.

Statistics on Lung Abscess

Generally, anyone with a bad chest infection can develop a lung abscess. It is difficult to estimate the true incidence of lung abscesses. They are more common with certain bacterial causes of pneumonia (Klebsiella pneumoniae, Staphylococcus aureus), and can be caused by aspiration. Aspiration is when somebody inhales mouth contents, often seen in impaired conscious states and in alcoholism.

Risk Factors for Lung Abscess

There are a number of possible predisposing factors, including aspiration, obstruction of the large airways in the chest, and direct inoculation. Immunosuppression can also contribute to the development of an abscess, as can alcoholism.

Progression of Lung Abscess

Usually the abscess develops because the original infection was not completely treated. Complications of a lung abscess include haemorrhage, septic emboli and amyloidosis. Extension across interlobar fissures and into the pleural cavity (empyema) develops in 20-30% of people with a lung abscess.

Symptoms of Lung Abscess

Generally the development of an abcscess will require hopitalisation and diagnostic testing. Some may be treated on an outpatient basis, but the possible need for radiology, ultrasound services or body posture for drainage may require some time in hospital. Most patients will fully recover.

Clinical Examination of Lung Abscess

There is not a lot of physical examination involved in the diagnosis and management of a lung abscess but the doctor will, especially at the initial consultation do a complete physical examination which will involve listening to the chest and heart.

How is Lung Abscess Diagnosed?

  • A full blood count will show increased white cells. Platelets, ESR and CRP will be raised.
  • Blood and sputum cultures should be performed to help isolate the organism.
  • A chest x-ray will demonstrate a rounded, cavitating, walled opacity with a fluid level.

Prognosis of Lung Abscess

Most patients with abscesses will recover with antibiotic treatment alone. Others, however, may need some minor surgery to aid in resolving the abscess

How is Lung Abscess Treated?

Other diagnoses such as tuberculosis, fungal infections, carcinoma, pulmonary infarction and pulmonary vasculitis should be ruled out. Regular postural drainage and chest physiotherapy will help to drain the purulent secretions. Antibiotic therapy ca be started, it should continue for a considerable length of time (4-6 weeks) – longer than for a usual lung infection. Bronchoscopy can allow drainage of pus and further diagnostic options. Aspiration or open surgical excision may be required.

Lung Abscess References

  1. Ramzi S. Cotran VK, Tucker Collins , Stanley L. Robbins. Pathologic Basis of Disease. Seventh ed: W.B. Saunders Company; 2005.
  2. Mansharamani. Chronic lung sepsis: lung abscess, bronchiectasis, and empyema. Current Opinion in Pulmonary Medicine. 2003; 9(3): 181-5.
  3. Hirshberg. Factors predicting mortality of patients with lung abscess. Chest. 1999; 115(3): 746-50.
  4. Neild JE, Eykyn SJ, Phillips IAN. Lung abscess and empyema. QJM. 1985; 57(3-4): 875-82.
  5. Tanaka T, Inaba Y, Arai Y, Matsueda K, Aramaki T, Dendo S. Mediastinal abscess successfully treated by percutaneous drainage using a unified CT and fluoroscopy system. Br J Radiol. 2002; 75(893): 470-3.