Lung Abscess

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A lung abscess is defined as necrosis of the pulmonary parenchyma and formation of cavities containing necrotic tissue or purulent fluid, usually caused by microbial infection. Antibiotic management should be considered as soon as it is diagnosed, while awaiting confirmation of the causative organism and must be continued for 4-6 weeks.

Cause

  • Aspiration of infected secretions or tissue from the mouth and upper respiratory tract in the unconscious or semi-conscious patient e.g. in  alcoholics, epileptics, anaesthetised or dental patients 
  • Foreign body aspiration e.g. inhaled peanut, dentures, fish bone
  • Inadequately treated bacterial pneumonia especially, gram negative bacteria like Klebsiella pneumoniae, and beta-haemolytic streptococci
  • Staphylococcus aureus causing multiple lung abscesses
  • Penetrative lung injury
  • Partial obstruction of an airway by tumour or lymph node
  • Septic emboli from other infected areas of the body e.g. right sided bacterial endocarditis
  • Bronchiectasis
  • Infected bullae in chronic lung disease

Symptoms

  • Fever with swinging temperatures
  • Cough, productive of copious amounts of purulent foul smelling sputum
  • Haemoptysis
  • Chest pain 
  • Breathlessness
  • Easy fatiguability

Signs

  • Fever
  • Tachycardia
  • Tachypnoea
  • Chest wall tenderness
  • Dull percussion note
  • Diminished breath sounds
  • Increased vocal resonance 

Investigations

  • FBC
  • Sputum culture and sensitivity, gram stain
  • Sputum AFBs
  • Chest X-ray 

TreatmentTreatment Objectives

  • To drain abscess collection
  • To treat underlying infection
  • To treat predisposing conditions

Non-pharmacological treatment

  • Chest physiotherapy 
  • Improve nutritional status
  • Ensure adequate fluid intake 
  • Surgical drainage of abscess

Pharmacological treatment 

Initial treatment

1st Line Treatment

Evidence Rating: [B]

  • Cloxacillin, IV, 

Adults

500 mg 6 hourly for 4 weeks

Children 

5-12 years; 250 mg 6 hourly for 2-4 weeks

1-5 years; 125 mg 6 hourly for 2-4 weeks

< 1 year; 62.5 mg 6 hourly for 2-4 weeks 

And

  • Amoxicillin + Clavulanic Acid, IV,

Adults

1.2 g 8 hourly for 4 weeks  

Children

3 months -18 years; 30 mg/kg 8 hourly, max. 1.2g 8 hourly

< 3 months; 30 mg/kg 12 hourly for 2-4 weeks

And

  • Ceftriaxone, IV, 

Adult

2 g daily for 4 weeks

Children

All ages 50-75mg /kg per day in divided 12 hourly doses for 4 weeks

Or

  • Gentamicin, IV,

Adults

40-80 mg 8 hourly for 14 days

Children

1-12 years; 2.5 mg/kg 8 hourly for 14 days

< 1 year; 2.5 mg/kg 12 hourly for 14 days

And

  • Metronidazole, IV,

Adults

500 mg 8 hourly for 4 weeks

Children

7.5 mg/kg 8 hourly for 4 weeks

Or

  • Clindamycin, IV,

Adults

300-600 mg 6 hourly for 4 weeks or until clinical improvement

Children

3-6 mg/kg 6 hourly for 2-4 weeks

Continuation treatment 

  • Flucloxacillin, oral, 

Adults

500 mg 6 hourly for 2 weeks

Children 

5-12 years; 250 mg 6 hourly for 2 weeks

1-5 years; 125 mg 6 hourly for 2 weeks

< 1 year; 62.5 mg 6 hourly for 2 weeks 

And

  • Amoxicillin + Clavulanic Acid, oral,  

Adults

1 g 12 hourly for 14-21 days.

Children

> 12 years; One 500/125 tablet 12 hourly

6-12 years; 5 ml of 400/57 suspension 12 hourly 

1-6 years; 2.5 ml of 400/57 suspension 12 hourly 

1 month-1 year; 0.25ml/kg body weight of 125/31 suspension 8 hourly 

< 1 month; 0.25 ml/kg body weight of 125/31 suspension 8 hourly 

And 

  • Clindamycin, oral, 

Adult

300 mg 6 hourly for 14 days

Children

> 3 months; 15-40 mg/kg/day, in 3 divided doses, (Minimum dose - not less than 300 mg/day)

Referral Criteria

  • Refer to a specialist or higher-level facility if there is no clinical improvement within the first 2 weeks of initiating antibiotic therapy.