Effect of Topical Antibiotic Prophylaxis on Conjunctival Flora and Antibiotic Resistance Following Intravitreal...

We sought to determine changes in the conjunctival bacterial flora and antibiotic resistance after topical antibiotic drops for infection prophylaxis were administered following intravitreal injections in patients with type 2 diabetes.

This prospective and nonrandomized cohort study included 116 eyes of 116 treatment-naive patients with type 2 diabetes who received six serial intravitreal anti-vascular endothelial growth factor injections for macular edema. Three conjunctival cultures were obtained from each eye over the course of the study (Culture 1, baseline; Culture 2, 1 month after the third injection; and Culture 3, 1 month after the sixth injection). The study subjects were given topical moxifloxacin hydrochloride for 4 days after each monthly intravitreal injection. The growth patterns of conjunctival bacterial flora and the antibiotic resistance to several commonly used antibiotics were examined.

The rate of culture positivity increased significantly during the observation period (Culture 1, n = 47, 40.5%; Culture 2, n = 58, 50%; Culture 3, n = 76, 65.5%, p < 0.001). The bacterium with the highest baseline culture positivity was Staphylococcus epidermidis (n = 45, 38.8%), which increased significantly during the observation period (p < 0.001). No significant increase was noted in the culture positivity of the other bacteria with baseline culture positivity (p > 0.05). Regarding antibiotic susceptibility, significant increases in resistance to the fluoroquinolone group of drugs were noted (p < 0.001). No significant changes in sensitivity were detected in the other 11 investigated antibiotics that are commonly used in clinical practice (p > 0.05).

The use of topical moxifloxacin after each intravitreal injection significantly increases the fluoroquinolone resistance of the ocular surface flora and the culture-positivity rate of S. epidermidis in patients with type 2 diabetes.