A 5-year-old child presents with fever, painful unilateral periorbital swelling, proptosis, and restricted eye movements. CT shows involvement of the orbit beyond the orbital septum. Which organism is most commonly responsible in the pre-vaccine era?

• A Staphylococcus aureus
• B Streptococcus pneumoniae
• C Haemophilus influenzae type b ✓
• D Pseudomonas aeruginosa

Explanation

Orbital cellulitis (post-septal) presents with proptosis, restricted eye movements, and vision changes, distinguishing it from preseptal cellulitis. In the pre-vaccine era, Haemophilus influenzae type b was the most common cause of orbital cellulitis in children. Hib conjugate vaccine has dramatically reduced this. S. aureus and S. pneumoniae are also causes but Hib was classically the most common.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.