Also known as : Necrotizing Pneumonia or Lung Gangreene .

What is it ?

     Lung abscess is a localised area of necrosis of lung tissues with development of fluid filled cavities .

Etiopathogenesis :

     Microorganisms commonly isolated from lesions of lung abscess are Streptococci , Staphylococci , anaerobic organisms like Bacterioids and a host of gram negetive organisms .

They are introduced into the lungs by the following mechanisms -

a) Aspiration of infected material ( commonest cause ) : like food , decaying teeth ,gastric contents , necrotic tissue from lesions in the mouth , upper respiratory tract , nasopharynx .

b) Preceding bacterial infection - like S.aureus , Pseudomonus aerugenosa , K.pneumonie or infective conditions like tuberculosis ,bronchiectasis .

c) Bronchial obstruction .
d) Septic embolism - from thrombophlebitis , pyaemia or vegetative bacterial endocarditis .

e) Neoplasia .

f) Miscellaneous - trauma to lungs ; infection spreading from neighbouring organs ; infections due to pyogenic organisms .

Clinical course :

   - Patients show symptoms like fever ,cough with foul smelling & bad testing sputum , chest pain , weight loss .

   - There may be decreased breath sounds , course crackling sounds during inspiration , dulness to percussion & contralateral shift of mediastinum .

   - Clubbing of fingers and toes may appear within a few weeks after the onset of abscess .

Laboratory investigations :

a) TLC & DC reveals leukocytosis .

b) Sputum for Gram staining , Acid-fast staining , culture obtained .

c) Blood culture may be done .

d) Imaging studies - Chest X-ray , CT scan & USG imaging may be done .

e) Tissue biopsy and histological investigations to be done .

What are the treatments available ?

Antibiotic therapy lasting for 4-6 weeks are usually perscribed .

The commonly used antibiotics are :-

- Clindamycin

- Penicilin G

- Cefoxatin

- Metronidazole

- Ampicillin + Sulbalactum + Cephalosporin( occationally )

- Moxifloxacin

If conventional therapy fails lung abscesss drainage or surgical resection is considered .

How to privent this disorder ?

a) Early intubation .

b) Positioning patient at 30 degree reclined angle .

c) Oral hygine & dental care decreases risk .

What are the complications arising in this disorder ?

a) Empyema

b) Fibrosis of pleura 

c) Pleural cutaneous fistula

d) Hemorrhage

e) Brain abscess or meningitis from septic emboli .

f) Secondary amyloidosis ( rarely )

Prognosis :

     The prognosis of  lung abscess following antibiotic therapy is generally favourable with about 90% being cured due to medication alone , unless caused by bronchial obstruction secondary to carcinoma .

Article written by : A . Biswas, MBBS(std)