Efficacy of Vitrectomy in Improving the Outcome of Bacillus Cereus Endophthalmitis

In Brief Purpose: To evaluate the efficacy of vitrectomy with vancomycin for the treatment of experimental Bacillus cereus endophthalmitis. Methods: Endophthalmitis was initiated in rabbits via intravitreal injection of 100 colony-forming unit B. cereus. Treatment groups included 25-gauge transconjunctival sutureless vitrectomy with intravitreal vancomycin (1 mg) or vancomycin alone. Groups were treated at 4, 5, or 6 hours after infection. At 48 hours (for 4-hour and 5-hour groups) or 36 hours (for the 6-hour group) after infection, eyes were analyzed by electroretinography, histology, and inflammatory cell counts. Results: Treatment with vitrectomy/vancomycin at 4 hours resulted in significantly greater retinal function compared with that of vancomycin alone. Intraocular inflammation after treatment at 4 hours was minimal for both the treatment groups. Treatment with vitrectomy/vancomycin or vancomycin alone at 5 hours or 6 hours after infection resulted in similar levels of retinal function loss (i.e., >90%) and significant intraocular inflammation. Conclusion: These results demonstrate that vitrectomy may be of therapeutic benefit in the treatment of B. cereus endophthalmitis but only during the early stages of infection. Bacillus cereus causes one of the most visually devastating and aggressive forms of endophthalmitis that is often associated with trauma. Recently, we reported that early antibiotic treatment of this infection is essential for preservation of useful vision and that vancomycin effectively sterilized the eye and limited significant inflammation during infection. This study analyzed whether vitrectomy in combination with vancomycin can improve the visual outcome of experimental B. cereus endophthalmitis over that of vancomycin alone, especially when treatment is delayed.