Effect of Topical Antibiotic Prophylaxis on Conjunctival Flora and Antibiotic Resistance Following Intravitreal Injections in Patients with Type 2 Diabetes

Purpose: We sought to determine changes in the conjunctival bacterial flora and antibiotic resistance after topical antibioticdrops for infection prophylaxis were administered following intravitreal injections in patients with type 2 diabetes. Methods: This prospective and nonrandomized cohort study included 116 eyes of 116 treatment-naive patients with type2 diabetes who received six serial intravitreal anti-vascular endothelial growth factor injections for macular edema. Threeconjunctival cultures were obtained from each eye over the course of the study (Culture 1, baseline; Culture 2, 1 month afterthe third injection; and Culture 3, 1 month after the sixth injection). The study subjects were given topical moxifloxacinhydrochloride for 4 days after each monthly intravitreal injection. The growth patterns of conjunctival bacterial flora and theantibiotic resistance to several commonly used antibiotics were examined. Results: The rate of culture positivity increased significantly during the observation period (Culture 1, n = 47, 40.5%; Culture2, n = 58, 50%; Culture 3, n = 76, 65.5%, p < 0.001). The bacterium with the highest baseline culture positivity was Staphylococcusepidermidis (n = 45, 38.8%), which increased significantly during the observation period (p < 0.001). No significant increasewas noted in the culture positivity of the other bacteria with baseline culture positivity (p > 0.05). Regarding antibioticsusceptibility, significant increases in resistance to the fluoroquinolone group of drugs were noted (p < 0.001). No significantchanges in sensitivity were detected in the other 11 investigated antibiotics that are commonly used in clinical practice (p >0.05). Conclusions: The use of topical moxifloxacin after each intravitreal injection significantly increases the fluoroquinolone resistanceof the ocular surface flora and the culture-positivity rate of S. epidermidis in patients with type 2 diabetes.