Lung Abscess
Definition
Lung abscess is necrosis of the pulmonary tissue and formation of cavities filled with pus
Causes
Primary results from existing lung parenchymal process
Secondary when it complicates another process e.g. vascular emboli or follows rupture of extrapulmonary abscess into lung.
Conditions contributing to lung abscess
Aspiration during altered consciousness. Aspiration of oropharyngeal or gastric secretion
Alcoholism
Septic emboli
Necrotizing pneumonia Pneumonitis - bacterial, tuberculous
Vasculitis: Wegener's granulomatosis
Necrotizing tumors: primary squamous carcinoma of the lung is the commonest.
Organisms
Anaerobic bacteria: Peptostreptococcus, Bacteroides, Fusobacterium species,
Microaerophilic streptococcus : Streptococcus milleri
Aerobic bacteria: Staphylococcus, Klebsiella, Haemophilus, Pseudomonas,Nocardia, Escheria coli, Streptococcus, Mycobacteria
Fungi: Candida, Aspergillus
Parasites: Entamoeba histolytica,
Symptoms
Cough - productive - foul smelling purelent sputum
Haemoptysis
Fever with shivering and night sweats
Chest pain
Dyspnoea
Lethargy
And other features of chronic illness.
Patients are cachectic
Finger clubbing
Signs of consolidation such as localised dullness on percussion, bronchial breath sound
Diagnosis
Chest Xray, CT scan, MRI scan
Abscess is often unilateral
Single
Involving posterior segments of the upper lobes and the apical segments of the lower lobes (gravity dependent when lying down.)
Presence of air-fluid levels implies rupture into the bronchial tree
Laboratory studies
High ESR
High CRP
Mixed flora.
Transtracheal of Transbronchial (via bronchoscopy) aspirates can also be cultured.
Fibre optic bronchoscopy - to exclude obstructive lesion; it also helps in bronchial drainage of pus.
Management
Broadspectrum antibiotic
Pulmonary physiotherapy and postural drainage
Surgical procedures are required in selective patients for drainage or pulmonary resection.
Complications
Spread of infection to other lung segments
Bronchiectasis
Empyema
Bacteraemia with metastatic infection such as brain abscess
Prognosis
Most cases respond to antibiotic and prognosis is usually excellent unless there is a debilitating underlying condition.
Mortality 5%
