Coryneform group A-4 endophthalmitis: An experimental animal model

Diphtheroids, members of the coryneform family of bacteria, increasingly have been recognized as the cause of serious ocular diseases. After isolation of coryneform group A-4 from two patients with delayed endophthalmitis after cataract extraction and intraocular lens implantation, 10⁷ organisms were injected into the vitreous of seven New Zealand white rabbits, producing endophthalmitis in all eyes inoculated. Coryneform group A-4 subsequently was isolated in six of seven eyes receiving 10⁷ organisms, proving Koch's postulates. Five of these seven eyes were treated with a single dose of intravitreal gentamicin, and three eyes remained culture positive. Eyes inoculated with 10⁵ or 10² coryneform group A-4 organisms had transient anterior chamber and vitreal inflammation; all vitreous cultures were negative. These studies demonstrate that coryneform group A-4 endophthalmitis can be reproduced in an animal model and that gentamicin may not sterilize an eye infected with this organism. Future studies are needed to determine the optimum antibiotic regimen for treatment of this type of endophthalmitis.