9. Purulent diseases of lungs – lung abscess, necrotizing pneumonia · Internal Diseases – Part 1 (Rheumatology, Pulmonology, Phthisiatrics, Cardiology, Haematology) · MU Plovdiv

Lung abscess

Necrosis of the pulmonary tissue and formation of cavities containing necrotic debris or fluid caused by microbial infection.
Formation of multiple small abscesses is referred to as necrotizing pneumonia or lung gangrene

Polyetiological, most common organisms are:
Anaerobic bacteria- Bacteroides, Prevotella, Peptostreptococcus, Fusobacterium, or streptococci
Monomicrobial lung abscess- caused by streptococci, Staphylococcus aureus, Klebsiella pneumoniae

Lung abscess formed in course of lobar pneumonia, bronchiectasis, carcinoma and infraction.
There are two periods in course of lung abscess:
First period- till penetration in communicating bronchus (organised abscess)
Period after cavity has been evacuated (open abscess)

Symptoms depend on whether abscess is caused by anaerobic or other bacterial infections:
Acute onset of fever
Cough with expectoration
Haemoptysis with foul smelling sputum
Chronic illness with debilitation
Pleuritic pain
Night sweats
Anorexia
Weight loss
Gingival disease can be seen

Inspection- patient very intoxicated, clubbing fingers (in chronic abscess). Damaged chest half is delaying in respiration
Palpation- when cavity full of pus vocal fremitus is weak. When cavity empty it is more pronounced
Percussion- when abscess is full, dull sound is tapped. When abscess is empty tympanic sound detected
Auscultation- when full, weak vesicular breathing and medium or large wet ronchi. When empty, cavernous bronchial breathing is heard

White cell count- may reveal leukocytosis and left shift
Obtain sputum for gram stain, culture and sensitivity
If TB suspected, acid-fast bacilli stain and mycobacterial culture requested
Chest radiography- typical appearance of abscess is irregular shaped cavity with air-fluid level inside
CT- abscess is rounded radiolucent lesion with thick wall and ill-defined irregular margins

Empiric coverage should target colonized organisms in upper airway and oropharynx like gram-positive cocci, respiratory gram-negative cocci, aerobic, and anaerobic gram negative bacilli
For methicillin-resistant Staphylococcus aureus (MRSA), vancomycin or linezolid are preferred.
Antibiotic duration is usually around three weeks but varies depending on clinical response.
Consider switching to per oral (PO) antibiotics once patients are afebrile, stable, and able to tolerate an oral diet