A topic of lung abscess

1. Prepared by Sayed Mohd Suleman
Group: 513
Lung Abscess:
Understanding
Causes,
Pathogenesis,
Diagnosis &
Treatment

2. What is a Lung Abscess?
A lung abscess is a localized pus-filled cavity within the lung tissue. This
serious condition arises from infection and subsequent tissue necrosis.
Typically, it measures more than 2 cm in size, containing necrotic debris
and fluid.
It often develops gradually, commonly following events like aspiration of
foreign material or as a complication of pneumonia.

3. Causes of Lung Abscess
Primary Cause: Aspiration
Most commonly, lung abscesses
result from the aspiration of
oropharyngeal secretions, which
carry oral flora and anaerobic
bacteria into the lungs.
Risk Factors
Key predisposing factors include
alcoholism, altered
consciousness, poor oral hygiene,
and neurologic disorders that
impair swallowing reflexes.
Secondary Causes
Other causes include bronchial
obstruction (e.g., by tumors or
foreign bodies), hematogenous
spread (septic emboli), and direct
extension from adjacent
infections.

4. Pathogenesis: How Lung Abscess
Develops
Aspiration events introduce a mix of
aerobic and anaerobic bacteria into the
lung parenchyma.
01 02
Bacterial Introduction Inflammation & Necrosis
The presence of these bacteria triggers an
intense inflammatory response, leading to
tissue necrosis and the formation of a pus-
filled cavity.
03
Abscess Maturation
The abscess grows, often rupturing into a bronchus, which can result in the production
of foul-smelling sputum.
Potential Complications
Severe complications include empyema, bronchopleural
fistula, and sepsis.

5. Common Pathogens Involved
1
Anaerobes
Peptostreptococcus, Fusobacterium, Bacteroides,
Prevotella are frequently isolated, often
originating from the oral cavity.
2
Aerobes
Common aerobic culprits include Streptococci,
Staphylococcus aureus (including MRSA), and
Klebsiella pneumoniae.
3
Immunocompromised
In patients with weakened immune systems,
pathogens like Pseudomonas, Nocardia, and
fungi (e.g., Candida, Aspergillus) can cause
lung abscesses.

6. Clinical Presentation & Symptoms
Gradual Onset of Symptoms
Patients typically experience a gradual onset of symptoms that can include:
• Persistent fever
Productive cough with foul-smelling sputum
Drenching night sweats and significant weight loss
Chest pain, difficulty breathing (dyspnea), and
general malaise are also common.
Physical Examination Findings
A physical exam may reveal localized dullness to percussion, bronchial

7. Diagnostic Approach
Chest X-ray
Often the initial imaging,
revealing a cavity with an air-
fluid level, commonly in
dependent lung segments like
the right lower lobe.
CT Scan (Gold Standard)
Provides detailed visualization
of abscess size, wall
thickness, and any associated
complications, crucial for
diagnosis.
Microbiology & Labs
Sputum Gram stain and culture identify pathogens. Bronchoscopy
may be needed for suspected obstruction. Blood cultures and lab
tests help confirm infection and rule out other conditions like
cancer or TB.

8. Treatment Strategies
Antibiotic Therapy
Prolonged courses of broad-spectrum antibiotics are crucial, targeting
both anaerobes and aerobes (e.g., beta-lactam/beta-lactamase inhibitors,
carbapenems). Treatment typically lasts 3-8 weeks, guided by clinical and
radiologic response.
Drainage Procedures
Percutaneous drainage is considered for abscesses larger than 6 cm
or those not responding to antibiotics alone.
Surgical Intervention
Surgery (lobectomy) is rarely required, reserved for severe
complications or when malignancy cannot be ruled out.
Supportive Care
Includes ensuring adequate hydration, nutrition, and effective
airway clearance to aid recovery.

9. Complications & Prognosis
Bronchopleural Fistula
Abnormal connection between bronchus and pleural space.
Massive Hemoptysis
Severe bleeding from the respiratory tract.
Sepsis
Life-threatening organ dysfunction caused by a dysregulated host response to
infection.
Empyema
Collection of pus in the pleural cavity.
While complications like empyema, bronchopleural fistula, massive hemoptysis, and chronic abscess formation can occur, overall mortality has been reduced
with advancements in treatment.
However, prognosis remains guarded for elderly and immunocompromised patients. Most patients achieve full recovery with timely and appropriate therapy.

10. Summary & Takeaway
Necrotizing Infection
A lung abscess is a serious necrotizing lung infection, primarily resulting from aspiration of oral contents.
Early Recognition
Timely diagnosis through imaging and microbiology is paramount for effective management and improved outcomes.
Antibiotic Cornerstone
Prolonged antibiotic therapy remains the cornerstone of treatment; drainage or surgery are reserved for specific cases.
Prevention & Care
Good oral hygiene and strategies to prevent aspiration are crucial in reducing the risk of developing lung abscesses.