Prevalence of Bacterial Contamination of Needles Following Intravitreal Injection of Triamcinolone Acetonide

Abstract

Abstract: : Purpose: Endophthalmitis is a rare but serious complication following intravitreal injections. The goal of this study is to determine the percentage of needles that are used for intravitreal injection of triamcinolone acetonide (IVTA) become contaminated with bacteria during the injection process. Methods: A total of 17 eyes from 16 patients scheduled to undergo IVTA as a treatment of macular degeneration were enrolled in this prospective non–randomized study. All patients received topical antibiotic one to three times in five–minute intervals fifteen minutes before injection in addition to an application of 5% povidone–iodine (PVI) swab to the periorbital area and conjunctiva. Cultured samples were obtained at baseline from both the palpebral conjunctival sac (csT0) and the bulbar conjunctival injection site (cT0), using a moistened cotton swab, and after the application of both topical antibiotic and PVI from the bulbar conjunctival injection site only (cT1), using a dry cotton swab. The cotton swabs and the needles that had been used for the injections were inoculated and incubated at 37°C for 5 days in blood culture broth. Results: At baseline, the percentage of the csT0 and cT0 cultured samples positive for bacterial growth were 41.2% (7 eyes) and 47% (8 eyes), respectively. Following the application of topical antibiotics and PVI, the percentage of positive cT1 cultured samples were 17.6% (3 eyes). Only one needle (5.9%) had positive culture for coagulase–negative Staphylococcus (P = 0.0167). Coagulase–negative Staphylococcus (85.7%) was the most common bacteria among the total of 14 isolated strains. Conclusions: Prophylaxis with topical antibiotic and PVI reduces conjunctival bacterial flora in patients undergoing IVTA. The needles used for the intravitreal injection can become contaminated with bacteria during the injection process. This may represent one mechanism of inoculation of bacteria into the vitreous cavity.

Keywords: endophthalmitis • bacterial disease • antibiotics/antifungals/antiparasitics