– Localized collection of pus in lung tissue often resulting from bacterial infections
– Forms cavities with necrotic debris, inflammatory cells, and bacteria

– Liquefactive necrosis of lung tissue
– Formation of cavities >2 cm filled with necrotic debris or fluid
– Surrounded by a fibrous reaction (abscess wall)
– Multiple small abscesses can occur, known as necrotizing pneumonia

– Primary: Arising from existing lung issues (e.g., pneumonia)
– Secondary: Complicating other conditions (e.g., vascular emboli)

– Primary cause: Aspiration of oral or gastric contents into the lungs.
– Higher risk: Individuals with impaired consciousness (e.g., alcohol/drug intoxication, neurological disorders), swallowing difficulties, and immunocompromised individuals.

– Aspiration of anaerobic organisms from the mouth (common in aspiration pneumonia).
– Complications from respiratory infections like pneumonia or bronchiectasis.
– Systemic conditions that weaken immunity, such as alcoholism or immunodeficiency.

– Primary abscess: Occurs in previously normal lungs, often following aspiration.
– Secondary abscess: Develops in patients with underlying lung abnormalities or as a complication of another condition.

Anaerobes:
– Peptostreptococcus spp.
– Bacteroides spp.
– Fusobacterium spp.
– Microaerophilic streptococci

Aerobes:
– Staphylococcus aureus
– Streptococcus pyogenes
– Haemophilus influenzae
– Pseudomonas aeruginosa
– Klebsiella pneumoniae
– Burkholderia cepacia (associated with cystic fibrosis)
– Streptococcus pneumoniae
– Legionella pneumonia
– Actinomyces spp.
– Nocardia spp.
– Proteus mirabilis
– Pasteurella multocida (zoonotic from cats/dogs/cattle)
– Burkholderia pseudomallei (causing melioidosis)

Other organisms:
– Mycobacterial infections (e.g., TB)
– Fungal lung infections (e.g., Aspergillus, Cryptococcus, Histoplasma, Blastomyces, Coccidioides species)
– Parasites (e.g., Entamoeba histolytica, Paragonimus spp.)

– Medical conditions that increase the risk include:
– Diabetes mellitus.
– Congenital heart disease.
– Neurological conditions such as stroke, cerebral palsy, and cognitive impairment.
– Chronic lung diseases (e.g., cystic fibrosis, bronchiectasis).
– Immunosuppression (e.g., HIV/AIDS, immunosuppressive therapy).

– Lifestyle factors include:
– Alcoholism or drug misuse.
– Smoking.
– Poor dental hygiene.

– Conditions leading to impaired consciousness, thus increasing the risk of aspiration, include:
– Alcohol or drug intoxication.
– General anesthesia.
– Neurological conditions (e.g., stroke, cerebral palsy, cognitive impairment).

– Factors include:
– Poor dental hygiene and severe periodontal disease.
– Dysphagia (swallowing difficulties).

– Immunosuppression (e.g., HIV/AIDS or immunosuppressive therapy) weakens the immune system, making the individual more susceptible to lung infections and abscess formation.

– Formation involves:
– Bacterial colonization from oral or gastric contents due to aspiration.
– Impaired host defenses and predisposing factors.
– Bacterial multiplication leading to infection and an inflammatory response.
– Tissue destruction results in cavity formation and abscess development.
– Accumulation of debris, inflammatory cells, and bacteria within the abscess.

– Commonly secondary to aspiration pneumonia.
– Risk factors include poor dental hygiene, previous stroke, and reduced consciousness.
– Other causes include:
– Haematogenous spread (e.g., infective endocarditis).
– Direct extension (e.g., from empyema).
– Bronchial obstruction (e.g., lung tumor).

– Typically polymicrobial.
– Monomicrobial causes include Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa.

– Other chest infections: Pneumonia, tuberculosis (TB), opportunistic mycobacteria
– Neoplasia: Cavitating bronchial carcinoma
– Pulmonary infarction or embolism
– Vasculitis: Granulomatosis with polyangiitis
– Sarcoidosis with cavities
– Infected bronchogenic cyst
– Pulmonary fungal infections

– Incidence and prevalence: Limited data; exact figures not established
– Relatively rare compared to other respiratory infections
– More common in older individuals and those with underlying lung diseases or immunodeficiency
– Incidence influenced by risk factors, healthcare resources, and microbial patterns

– Persistent or recurrent fever
– Productive cough (often foul-smelling sputum)
– Chest pain
– Fatigue
– Weight loss
– Night sweats
– General malaise
– Hemoptysis (coughing up blood)
– Dyspnea (shortness of breath)

– Dull percussion
– Bronchial breathing
– Clubbing (in chronic cases)
– Tachypnea
– Tachycardia
– Dehydration
– High temperature
– Localized dullness to percussion (if consolidation or effusion is present)
– Crepitations (if consolidation is present)
– Signs of severe periodontal disease and infective endocarditis

– Lung abscesses may present acutely or chronically

– Primary abscess: Occurs in previously normal lungs, often following aspiration
– Secondary abscess: Develops in patients with underlying lung abnormalities

– Chest X-ray: Identifies fluid-filled spaces within areas of consolidation, typically shows an air-fluid level
– CT Scan of the Thorax: Detects multiple small abscesses not visible on X-ray

– Sputum and blood cultures are essential for identifying the causative bacteria and guiding antibiotic therapy

– Full Blood Count (FBC): May show normocytic anemia or neutrophilia.
– Renal Function and Liver Function Tests (LFTs): To assess organ function.
– ESR/CRP (Inflammatory Markers): Usually elevated.
– HIV

– Fibre-optic Bronchoscopy can exclude obstruction and provide samples for culture

– Trans-thoracic Biopsy/Aspiration: Performed with ultrasound guidance, helps in diagnosis when other tests are inconclusive
– Trans-tracheal Biopsy: Another option for obtaining diagnostic samples

– Antibiotics tailored to infection severity, local resistance, and patient factors
– Intravenous antibiotics for 2-3 weeks, followed by oral antibiotics for 4-8 weeks
– First-line therapy: Beta-lactam/beta-lactamase inhibitor or cephalosporin + clindamycin
– Adjust based on the causative organism

– Analgesia
– Oxygen therapy if needed
– Rehydration if indicated
– Postural drainage with physiotherapy

– Indications: No response to conservative treatment or presence of complications
– Procedures: Drainage via bronchoscope, CT-guided percutaneous drainage, or surgery
– Note: Surgery may carry complications, particularly in children

– Slow resolution may indicate malignancy or unusual organisms
– Successful antibiotic treatment occurs in 80-90% of cases
– Monitor and adjust the antibiotic regimen based on the causative organism and treatment response

– Prognosis depends on several factors:
– Infection severity
– Comorbidities
– Timely treatment
– Patient compliance
– Favourable prognosis with a 90% cure rate using appropriate antibiotic therapy and regular follow-up
– Complications such as rupture, septicaemia, and specific pathogens (e.g., Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae) can negatively impact outcomes
– Prognosis also influenced by age, underlying conditions, and reduced consciousness at the onset of infection

– Major complications include:
– Rupture leading to empyema (pus in the pleural space)
– Lung tissue scarring
– Bronchopleural fistula (communication between the bronchial tree and pleural cavity)
– Septicaemia (systemic infection)
– Distant organ abscesses from haematogenous spread