Real-time polymerase chain reaction in the diagnosis of acute postoperative endophthalmitis

Abstract

Purpose: To evaluate the efficacy of quantitative real-time polymerase chain reaction (qPCR) in the diagnosis of postoperative bacterial endophthalmitis among patients who underwent cataract surgery at a tertiary care center.

Design: Prospective experimental study.

Methods: This was a single-center study of 64 eyes of 64 patients presenting with clinical signs and symptoms of endophthalmitis within 1 year of cataract surgery. Patients with glaucoma filtering or cornea surgery in the past year, postoperative trauma, fungal endophthalmitis, or preoperative inflammatory conditions were excluded. Vitreous samples were obtained during vitreous tap or vitrectomy and sent for both culture and qPCR with sequencing. Vitreous samples obtained from 50 patients undergoing vitrectomy for noninflammatory indications served as controls. The main outcome measures were the sensitivity of qPCR compared to culture and concordance of results of pathogen identification with sequencing vs phenotypic speciation.

Results: qPCR detected 16s bacterial DNA in 37 patients (66%), compared to 19 (34%) with traditional culture. Only 1 patient had a positive result by culture (Nocardia species) but negative result by qPCR. For the 18 samples positive by both qPCR and culture, there was a 100% concordance in pathogen identification between sequencing and phenotypic speciation.

Conclusion: In cases of suspected bacterial endophthalmitis, qPCR offers an improved diagnostic yield and may be a useful adjunct to traditional culture. Further large-scale clinical studies are needed to elucidate the full clinical utility of qPCR.