[Clin Infect Dis 2012;Mar:e1-41]


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- Most common predisposing factor is viral upper respiratory tract infection (URTI). Bacterial sinusitis complicates only 0.5-2% of cases. Up to 10% of sinusitis may be related to dental disease.

- The role of Mycoplasma pneumoniae and Chlamydophila pneumoniae in acute sinusitis has been suggested but not substantiated. Empiric therapy for these organisms is not recommended.

Clinical presentation

- A bacterial etiology is more likely if:

  • high fever (≥ 39°C) and purulent nasal discharge or facial pain for 3-4 consecutive days at beginning of illness or

  • URTI symptoms persist for at least 10 days or worsen after 5-7 days with both nasal congestion/purulent nasal discharge and facial pain/pressure (usually unilateral)

  • fever
  • maxillary toothache
  • facial swelling.


- The colour of nasal discharge/sputum should not be used to diagnose the sinusitis episode as bacterial since colour is related to presence of neutrophils, not bacteria.

- Black, necrotic tissue or discharge in patients with poorly controlled diabetes/ketoacidosis, or with significant immunosuppression, may indicate mucormycosis. Recommend urgent ENT/ID consult.

- Nasopharyngeal cultures are not helpful in identifying etiological sinus pathogen(s).

- Sinus x-rays are not routinely recommended as they will not differentiate between viral URTI and bacterial sinusitis.

- CT scan only recommended for complications of acute sinusitis, chronic sinusitis not responding to therapy, and/or severe presentation.

- MRI not recommended due to poor bone definition.

- Transillumination of the sinuses is of limited value in adults.

Antibiotic Therapy

- The benefit of antibiotic therapy in sinusitis is controversial (~70% resolve spontaneously).

- Some guidelines recommend high-dose amoxicillin-clavulanate instead of amoxicillin for first line treatment of sinusitis because of high rates of penicillin-resistant S. pneumoniae and β-lactamase producing H. influenzae and M. catarrhalis.

- High-dose amoxicillin remains a reasonable first-line empiric option given:

  • the lower resistance rates in Canada

  • amoxicillin retains best coverage of all oral β-lactam agents against S. pneumoniae (even majority of penicillin-resistant strains)

  • higher incidence of adverse effects of amoxicillin-clavulanate

  • need to limit broad spectrum antibiotic use in order to minimize the development of antibiotic resistance.

- Macrolides, TMP/SMX, and oral cephalosporins are no longer recommended for empiric therapy of sinusitis due to unpredictable/poor activity against S. pneumoniae and/or H. influenzae.

- Levofloxacin has good coverage of the pathogens involved. However because of its broad spectrum, potential for increasing resistance, and risk of Clostridioides (Clostridium) difficile infection, it should be reserved for β-lactam allergic patients or patients who have failed first line antibiotic therapy.


  • limit spread of viral infections by handwashing

  • avoid environmental tobacco smoke

  • avoid allergen exposure.