PCR identification of Rhizobium radiobacter in post‐operative endophthalmitis

Abstract

Abstract Purpose: To present 2 cases of PCR identification of Rhizobium radiobacter in post‐operative endophthalmitis. Methods: Microbiological identification was carried out using samples from aqueous humor and/or vitreous. Conventional cultures were performed using a Brain Heart Infusion broth. We used broad‐range eubacterial PCR amplification followed by direct sequencing. Results: In both cases, Rhizobium radiobacter was identified using eubacterial PCR and cultures of vitreous from vitreous tap. An 81‐year‐old female presented an endophthalmitis 4 weeks after an cataract surgery. Inflammation and infection were controlled after 2 intravitreal antibiotic injections and the final visual acuity was of 20/24 at the one‐year follow‐up exam. A 75‐year‐old male who underwent a cataract surgery presented an endophthalmitis 9 days after. This patient was treated by 3 intravitreal antibiotic injections and a vitrectomy. The 6‐month follow‐up exam showed an optic nerve atrophy with a poor visual outcome (20/120). Both patients had an initial marked anterior chamber inflammation with a hypopyon and a severe retinal vasculitis was observed in the second case. Conclusions: Rhizobium radiobacter is a rare pathogen involved in postoperative endophthalmitis. As it is an environmental soil organism, we may assume that the patient's exposure to outdoor environnement and moist soil remains the source of this organism. This gram negative rod is resistant to vancomycin and have an intermediate resistance to most antibiotics used to treat post‐operative endophthalmitis. PCR allows a swifter bacterial identification than do cultures and may help choose the most efficient antibiotics.