Abstract
Purpose: :
The Antibiotic Resistance of Conjunctiva and Nasopharynx Evaluation (ARCANE) Study was a prospective, controlled, longitudinal study of patients designed to determine changes in resistance patterns of conjunctival bacteria after exposure to ophthalmic antibiotics. This study’s intent is to determine changes in ocular flora as a result of exposure to macrolide or fluoroquinolone ophthalmic antibiotics.
Methods: :
This was a prospective, controlled, longitudinal study of 48 eyes of 24 patients undergoing serial intravitreal (IVT) injections for choroidal neovascularization. All subjects received 4 consecutive monthly unilateral IVT injections and then were treated as needed. Subjects were randomly assigned to 1 of 4 antibiotics (azithromycin 1%, gatifloxacin 0.3%, moxifloxacin 0.5%, ofloxacin 0.3%) and used only their assigned antibiotic after each injection. Conjunctival cultures of the treated and untreated (control) fellow eye were taken at baseline and after each injection for 1 year. Bacterial isolates were tested for susceptibility against 16 antibiotics.
Results: :
At baseline, Staphyloccocus epidermidis and Staphylococcus aureus accounted for 54.5% and 18.2% respectively of isolates cultured from the conjunctiva of patients subsequently treated with azithromycin, compared to 45.7% and 6.5% of isolates from patients subsequently treated with fluoroquinolones. After treatment, S. epidermidis constituted 90.9% of isolates cultured from azithromycin-treated eyes which was significantly greater than at baseline (P < 0.001) and compared to fellow control eyes (P < 0.001). In fluoroquinolone-treated eyes, 63.4% of isolates were S. epidermidis which was significantly greater than at baseline (P = 0.02), but significantly less than azithromycin-treated eyes (P < 0.001). The percentage of S. aureus decreased significantly in azithromycin-treated eyes from 18.2% at baseline to 4.5% after treatment (P < 0.01) and there was a trend toward increased percentage of S. aureus in fluoroquinolone-treated eyes (13%) compared to azithromycin-treated eyes (4.5%, P = 0.08).There were no other observed differences among 12 other identified species of bacteria.
Conclusions: :
In this study, exposure to azithromycin appeared to increase the percentage of S. epidermidis to a greater degree than fluoroquinolones among conjunctival flora. In contrast, fluoroquinolone-treated eyes demonstrated a higher percentage of S. aureus.
Clinical Trial: :
http://www.clinicaltrials.gov 831961
Keywords: endophthalmitis • antibiotics/antifungals/antiparasitics • age-related macular degeneration