A 28-year-old presents with facial pain over the cheek, purulent nasal discharge and fever of five days duration. Transillumination suggests acute maxillary sinusitis. The MOST common bacterial cause of acute community-acquired sinusitis is:

• A Pseudomonas aeruginosa
• B Staphylococcus aureus
• C Streptococcus pneumoniae ✓
• D Anaerobic streptococci

Explanation

Streptococcus pneumoniae is the single most common isolate in acute community-acquired bacterial sinusitis, followed closely by Haemophilus influenzae, with Moraxella catarrhalis third. Staphylococcus aureus is more typical of nosocomial or chronic sinusitis, anaerobes dominate infections arising from dental origin, and Pseudomonas is seen in immunocompromised or hospitalised patients. Viruses cause the majority of acute 'sinusitis' presentations, so antibiotics are reserved for purulent, prolonged or severe illness.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.