Intravitreal linezolid in the management of vancomycin-resistant enterococcal endophthalmitis

Linezolid is a synthetic antibiotic, the first of the oxazolidinone class, used for the treatment of infections caused by multi-resistant bacteria including Streptococcus, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). We report on a case of endophthalmitis caused by vancomycin-resistant Enterococcus feacium treated with intravitreal linezolid. It has proved efficacious in animal models but its safety in humans is not fully known.

An 84-year-old man who had phacoemulsification surgery and anterior chamber intraocular lens due to posterior capsule rent. Visual acuity (VA) following surgery was 6/24 uncorrected. The following week he developed signs of endophthalmitis, characterized by corneal infiltration and keratic precipitates, with anterior chamber and vitreous haze. Cultures yielded no growth, while repeated treatments with intravitreal vancomycin, ceftazidime, and amphotericin B did not control the infection. Vitrectomy was performed twice during the patient's course, with intravitreal amikacin injection after the second vitrectomy, but poor control of the endophthalmitis persisted. After several weeks of limited response to treatments, the diagnosis was finally made using Giemsa stain of direct smear which showed characteristic morphology of Enterococcus faecium. Linezolid, one of the oxazo-lidinones, was initially given in oral form 600 mg BID for three weeks, but did not prove efficacious. Subsequently, intravitreal linezolid 200 mcg in 0.1ml was injected, which cleared the vitreous and cornea infection within a week. However, there was a residual exudative detachment of the retina in the posterior pole, leaving the patient with a final vision of hand movement.

Vancomycin-resistant enterococcus is a rare cause of endophthalmitis. Intravitreal linezolid is an effective treatment, but the subsequent exudative retinal detachment may have been related to this novel therapy.