Lung Abscess

Introduction

Lung abscess is defined as necrosis of the lung parenchyma, usually caused by microbial infection, often with an air-fluid level.

It may be classified as acute (symptoms < 1month) or chronic (symptoms> 1month).

It may also be classified as primary if it occurs in a previously healthy person or in a person prone to aspiration.

Secondary lung abscess commonly occurs in association with bronchogenic carcinoma or immunodeficiency states e.g. HIV infection.

Lung abscess may be associated with the following

Pyogenic bacteria
Tuberculosis
Fungi
Parasites
Pulmonary infarction
Primary or metastatic malignancies
Silicosis
Coal miner’s pneumoconiosis

Clinical features

Symptoms

Symptoms are indolent lasting several weeks. These include:

Cough, with purulent offensive sputum
Fever, chills
Night sweats
Weight loss
Pleurtic chest pain

Signs:

Digital clubbing
Crepitations
Pleural friction rub

Differential diagnoses

Localized bronchiectasis
Pneumonia
Tuberculosis

Complications

Cerebral abscess
Empyema
Amyloidosis

Investigations

Sputum: Gram stain and culture
Bronchoscopy
Transthoracic aspiration
Blood culture
Chest radiograph

Treatment objectives

Eradicate bacterial cause
Drain abscess
Preserve normal lung function

Non-drug treatment

Hydration
Pain relief
Physiotherapy

Drug treatment

Antibiotics

Metronidazole

Adult:

500mg orally every 8hours

Child:

neonate, initially 15mg/kg orally then 7.5mg/kg every 12 hours;
1 month – 12 years: 7.5 mg/kg (maximum 400mg) every 8 hours;
12-18years: 400mg every 8hours

Plus:

Amoxicillin

Adult:

500mg orally every 8 hours for 7 -10days