Treatment of experimental Bacillus cereus endophthalmitis using intravitreal moxifloxacin with or without dexamethasone.

PURPOSE: To evaluate the effects of intravitreal moxifloxacin with or without dexamethasone on experimental Bacillus cereus endophthalmitis.

METHODS

The right eyes of 21 New Zealand albino rabbits weighing 2-3 kg were used in this study. Each eye was inoculated with 1×10(6) colony-forming units of B. cereus microorganisms via intravitreal injection into the vitreous cavity, and an experimental model of B. cereus endophthalmitis was formed. The rabbits were separated into 3 groups: Group 1 was given 0.1 mL of balanced saline solution intravitreally, group 2 was given 50 μg of moxifloxacin, and group 3 was given 50 μg of moxifloxacin plus 400 μg of dexamethasone 24 h after the inoculation. Vitreous aspirates were taken for microbiological examination on the 3rd day. Clinical inflammation scores were evaluated on days 1, 7, and 14. The rabbits were killed on the 14th day, and the eyes were enucleated for histopathological examination.

RESULTS

On the 7th day, only the vitreous scores of the treatment groups were significantly low compared with those of the control group (P<0.05). On day 14, the clinical scores of vitreous inflammation were 2.43±0.79, 1.43±0.53, and 1.29±0.49 in Groups 1, 2, and 3, respectively. The clinical scores of the treatment groups were significantly lower compared with those of the control group on day 14 (P<0.05). Histopathological scores were 2.43±0.79, 1.43±0.53, and 1.43±0.79 for the iris and 2.14±0.69, 1.57±0.53, and 1.14±0.38 for the vitreous in Groups 1, 2, and 3, respectively. Apart from the conjunctiva, the histopathological scores of the other tissues in the treatment groups were significantly lower compared with those of the control group (P<0.05). No significant differences were found in the histopathological or clinical scores among the treatment groups (P>0.05). Microbiological scores at day 14 were 151±6.43, 125.43±13.44, and 131.14±16.99 for Groups 1, 2, and 3, respectively. The microbiological scores of the treatment groups were significantly lower compared with those of the control group (P<0.05).

CONCLUSIONS

Intravitreal moxifloxacin injection is effective in experimental B. cereus endophthalmitis. The addition of intravitreal dexamethasone may not significantly affect treatment efficacy.