Background Information

Definition

A self-limiting LRTI that causes bronchial airway inflammation

Causes

Viral infection (>90% of cases)

• Respiratory pathogens (e.g, Rhinovirus, Adenovirus, Coronavirus, Influenza, Parainfluenza)

Bacterial infection (1-10% of cases)

• Streptococcus pneumoniae
• Haemophilus influenzae
• Moraxella catarrhalis
• Rarer (usually in outbreaks): Mycoplasma pneumoniae, Chlamydophila pneumoniae, Bordetella pertussis 

Prognosis

• Typically mild self-limiting illness (cough usually lasts ~3-4 weeks)

Complications

• Pneumonia (secondary bacterial infection)
  • Commoner in older adults 
  • Sx: persistent fever/dyspnoea, abnormal lung findings 

Diagnosis Guidelines

Clinical Features

Clinical features:

• Cough +/- sputum production
• Systemic upset
• Fever may be absent or mild (high or persistent fever indicates pneumonia, influenza etc.)

Examination findings:

• Chest can be clear
• Wheezing
• Focal crackles are characteristically absent (presence suggests pneumonia)

Investigation and Diagnosis

Consider the following investigations:

• Pulse oximetry
• C-reactive protein (if clinical diagnosis of pneumonia has not been made and there is uncertainty about antibiotic use)
• Chest X-ray

Management Guidelines

Conservative / General Management

Advise on self-care strategies:

• Adequate fluid intake
• Analgesia – paracetamol / ibuprofen

Advise that some people may wish to try the following:

• Honey
• Pelargonium (herbal medicine)
• Expectorant (guaifenesin) – most useful for wet / productive cough
• Cough suppressants (except codeine) – to relieve dry non-productive cough
  • Should be avoided if there is sputum / mucus production (will worsen the cough)

Antibiotic Therapy

Do not routinely offer antibiotics to manage acute bronchitis

• Acute bronchitis is usually self-limiting, where the cough resolves after ~3-4 weeks
• Antibiotics do not make a large difference to the duration of symptoms

Indications

• Systemically very unwell
• Higher risk of complications
  • Pre-existing comorbid condition (e.g. heart / lung / kidney / liver / neuromuscular disease, immunosuppression, cystic fibrosis)
  • >65 yo with ≥2 or >80 y/o with ≥1 of the following:
    • Hospital admission in the previous year
    • Diabetes
    • Congestive heart failure
    • Current use of oral corticosteroids
• ↑ CRP level
  • CRP >100 mg/L → offer immediate antibiotic therapy
  • CRP 20-100 mg/L → consider delayed antibiotic prescription
  • CRP <20 mg/L → do not routinely offer antibiotics

Choice of Antibiotic

1st line: doxycycline

2nd line:

• Amoxicillin (safe in pregnancy and children)
• Clarithromycin
• Erythromycin

References

Original Guideline