Postoperative contamination after using vancomycin and gentamicin during phacoemulsification

Objective: To investigate if the addition of vancomycin and gentamicin to the irrigating solutions during phacoemulsification with lens implantation reduces the incidence of positive postoperative intraocular cultures. Design: Two-part, double-masked, placebo-controlled, randomized clinical trial. Patients: In the preliminary study, intracameral antibiotic concentrations were measured immediately after surgery (in 10 eyes) and 2 hours after surgery (in 10 eyes) in patients treated with antibiotics. In the primary study, 120 eyes underwent uncomplicated surgery. The treatment group and the placebo group were composed of 60 eyes each. Intervention: The treatment group received vancomycin, 20 mu g/mL, and gentamicin, 8 mu g/mL, in the irrigating fluid. The placebo group received only irrigating fluid. All patients in the primary study underwent anterior chamber aspiration following surgery, and culturing was performed 2 hours later. Main Outcome Measure: Identification and quantification of positive cultures in thioglycolate broth and chocolate agar. Result: In the preliminary study, the half-life of both intraocular antibiotics was less than 2 hours. In the primary study, intraocular aspirates yielded positive cultures in 3 specimens (5.0%) in the antibiotic-treated group and in 7 specimens (12.0%) in the placebo group. Conclusions: Although we found a higher rate of positive postoperative cultures in the placebo group (odds ratio = 2.51), 2 hours of contact between the antibiotic solution and bacteria did not produce results that reached statistical significance (P=.18) to support adding vancomycin and gentamicin to the irrigating solutions during phacoemulsification. Further studies are needed to evaluate the clinical implications of using antibiotics in irrigating solutions.