Effect of blood on susceptibility to Staphylococcal endophthalmitis

PURPOSE: The authors examined the effect of blood on susceptibility to experimental endophthalmitis. METHODS: Forty rabbits received an injection of 5-25 colony-forming units of Staphylococcus epidermidis into the vitreous of the right eye. Twenty of these same eyes received a subsequent intravitreal injection of 0.2 mL blood while the remaining 20 received an intravitreal injection of 0.2 mL of a salt solution. All eyes were examined daily for signs of endophthalmitis. Vitreous cultures were obtained on day 2 from 30 of the 40 rabbits. Twenty rabbits were assigned for culture and euthanasia at day 5 and those remaining were cultured and killed at day 7. RESULTS: In rabbits with blood and bacteria, 10 of 15 (67%) were culture positive at 2 days, compared to 2 of 15 (13%) that received salt solution and bacteria (P < 0.01). At days 5 and 7 there was no statistically significant difference in culture results. However, inflammatory scores were significantly higher at days 3-7 in rabbits with blood compared to those with salt solution (P