Effects of intravitreal corticosteroids in the treatment of Bacillus cereus endophthalmitis

Objective: To investigate whether intravitreal corticosteroid therapy reduces the extent of inflammatory intraocular tissue damage caused by Bacillus cereus endophthalmitis. Methods: New Zealand white rabbits were inoculated with 1 X 10(6) B cereus organisms and randomized to receive no treatment (control eyes; n=14), intravitreal vancomycin hydrochloride (n=13), or a combination of intravitreal vancomycin and dexamethasone sodium phosphate (n=13) after 24 hours. The eyes were examined and graded for clinical signs of infection and inflammation on days 7 and 14, followed by enucleation for histopathologic analysis. Results: Both treated groups had significantly less clinical sequelae than controls on day 7. By day 14, eyes given combination treatment had significantly less clinically graded corneal (P=.03) and conjunctival (P=.007) inflammation than eyes treated with vancomycin. Histopathologic analysis revealed a significant decrease in inflammatory changes between all treated eyes and controls at day 14. The only statistically significant difference between eyes given combination treatment and eyes given vancomycin alone was in the retina (P=.03). Conclusions: Intravitreal corticosteroids may enhance the recovery from B cereus endophthalmitis when given in conjunction with intravitreal antibiotics. The beneficial effect of corticosteroids is noted clinically, but not histologically, by day 14 after single-dose treatment in rabbits. Clinical Relevance: This study provides evidence that the use of intravitreal corticosteroids with antibiotics for the treatment of B cereus endophthalmitis may lead to an improvement compared with the use of antibiotics alone.