• Sinusitis is inflammation of the mucous membranes lining the paranasal sinuses.
  • The term is most commonly used to describe bacterial rhinosinusitis, which is a clinical diagnosis made by the presence of upper respiratory tract symptoms that have not improved in 10 days or have worsened after 5 to 7 days. Sinusitis may be classified in a number of ways.
    • Classification based on duration of symptoms:
      • Acute: persistent nasal and sinus symptoms for 10 to 30 days; worsening or new onset of nasal discharge, daytime cough, or fever after initial improvement; or concurrent high fever and purulent nasal discharge for the first 3 to 4 days of an acute upper respiratory infection (URI)
      • Subacute: clinical symptoms for 30 to 90 days
      • Chronic: symptoms lasting >90 days
      • Recurrent: acute sinusitis with 10 days of complete resolution between episodes; three episodes in 6 months or four in 1 year
    • Classification by severity of illness:
      • Persistent acute: >10 to 14 days but <30 days; nasal discharge and/or daytime cough
      • Severe acute: temperature of ≥39°C (102.2°F) with concurrent purulent nasal discharge for ≥3 days and/or facial pain, headache, or periorbital edema

General Prevention

  • Avoid allergen exposure and treat allergies if present.
  • Improve mucociliary clearance by increasing ambient humidity with a humidifier.


  • Normal sinus function depends on patency of paranasal sinus ostia, function of the ciliary apparatus, and secretion quality.
  • Secretions accumulate due to ostial obstruction, reduction in ciliary function, and overproduction.
  • Viral URIs and/or allergic rhinitis often precede(s) acute bacterial sinusitis.
  • Acute bacterial sinusitis is a complication of 5–10% of URIs.


  • Viral pathogens (e.g., rhinovirus, parainfluenza virus) are often recovered in respiratory isolates.
  • Most illnesses of short duration (<7 days) are thought to be due to viral infection and therefore should not be treated with antibiotics.
  • Chronic sinusitis is often secondary to allergic rhinitis, cystic fibrosis, environmental pollutants, or gastroesophageal reflux.
  • Most common bacterial pathogens:
    • Haemophilus influenzae, nontypeable (with Streptococcus pneumoniae, make up 30% of cases)
    • S. pneumoniae
    • Moraxella catarrhalis (10% of cases)
  • Other bacterial pathogens:
    • Group A streptococci
    • Group C streptococci
    • Peptostreptococci
    • Other Moraxella species
    • Streptococcus viridans
    • Eikenella corrodens
    • Staphylococcus aureus (infrequent but significant pathogen in orbital and intracranial complications)
    • Pseudomonas aeruginosa (in patients with cystic fibrosis)
    • Anaerobic organisms
  • Polymicrobial
  • Fungal pathogen: Aspergillus

There's more to see -- the rest of this topic is available only to subscribers.