A 31-year-old farmer sustains a soil-contaminated corneal laceration from a thorn. Eighteen hours later he presents with lid oedema, chemosis, a ring infiltrate, hypopyon, and rapidly progressive panophthalmitis despite broad-spectrum topical drops. The most likely causative organism is:
- A Coagulase-negative Staphylococcus
- B Bacillus cereus ✓
- C Haemophilus influenzae
- D Aspergillus fumigatus
Correct answer: B. Bacillus cereus
Explanation
Bacillus cereus is the classic cause of fulminant post-traumatic endophthalmitis following soil-contaminated penetrating injuries. Its toxins produce an explosive necrotising infection within 24 hours, often with a ring corneal infiltrate and panophthalmitis, and visual prognosis is poor even with prompt intravitreal vancomycin. Coagulase-negative staphylococci cause indolent post-surgical infections, and fungal endophthalmitis evolves over days to weeks rather than hours.
Reference: Kanski's Clinical Ophthalmology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.