Resistant strains of bacteria feared from repeated use of ophthalmic antibiotics

According to data recently published in Archives of Ophthalmology, repeated use of ophthalmic antibiotics post intraocular injections will cause an increase in incidences of resistant strains of conjunctival flora.

The study performed by Drs Stephen Kim and Hassanain Toma (Vanderbilt Eye Institute, Department of Ophthalmology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA) examined 48 eyes of 24 patients who were being treated for choroidal neovascularization (CNV) with unilateral intraocular injection.

Conjunctival cultures were taken bilaterally from both eyes (treated and untreated) at baseline and after each injection. All patients were randomly assigned to one of four different antibiotics and used only that antibiotic after each injection. Antibiotic susceptibility of the bacterial isolates was measured for 16 various antibiotics and pulse-field gel electrophoresis was used to analyse the bacteria DNA.

It was found that significant increases in drug resistance occurred in treated eyes, which led the team to conclude that conjunctival flora that is repeatedly exposed to antibiotics will result in resistant strains.