Prophylaxis of experimental Pseudomonas aeruginosa endophthalmitis after vitrectomy using ceftazidime in the irrigating solution

Purpose: To test the efficacy of ceftazidime in irrigating solution during vitrectomy to prevent experimental Pseudomonas aeruginosa endophthalmitis. Methods: Thirty-two rabbit eyes were divided into 6 groups. Vitrectomy using one of two different irrigating solutions was followed by intravitreal injection of P. aeruginosa: Group 1, balanced salt solution (BSS) followed by 100 colony-forming units (CFU) P. aeruginosa; Group 2, BSS fortified with ceftazidime 175 μg/mL (CBSS) followed by intravitreal injection of 100 CFU P. aeruginosa; Group 3, BSS followed by 500 CFU P. aeruginosa; Group 4, CBSS followed by 500 CFU P. aeruginosa; Group 5, BSS followed by 5000 CFU P. aeruginosa; and Group 6, CBSS followed by 5000 CFU P. aeruginosa. The eyes were examined clinically. Vitreous samples were cultured and histology was performed. Results: Group 1: Three of 5 eyes showed mild to moderate vitreous opacities. Group 2: No vitreous opacities developed. Group 3: All eyes demonstrated endophthalmitis. Group 4: All 6 eyes had clear vitreous with visible fundus. Group 5: Severe endophthalmitis occurred in all 6 eyes. Group 6: Four eyes had clearly visible fundus, 2 eyes had hazy vitreous with red reflex of the fundus. Bacterial growth in groups 3, 4, 5, and 6 was seen in 4/4, 1/6, 6/6, and 0/6 eyes, respectively. Conclusion: When 100-5000 CFU P. aeruginosa were injected after vitrectomy, ceftazidime in the irrigating solution inhibited the signs of intraocular inflammation, and the rate of positive bacterial culture. This revised version was published online in July 2006 with corrections to the Cover Date.