Application of Biome Representational In Silico Karyotyping to Pathogen Detection in Endophthalmitis

Abstract

Purpose: : Microbial culture fails to identify a causative organism in approximately 30% of cases of infectious endophthalmitis. We investigated the utility of a novel molecular pathogen detection technique called Biome Representational in silico Karyotyping (BRiSK) to aqueous and vitreous tap specimens from eyes diagnosed with endophthalmitis and compared this technique with routine culture.

Methods: : BRiSK is a recently described method of digital karyotyping that utilizes massively parallel sequencing of purified DNA to construct high-resolution karyotypes and can identify multiple foreign species within a given tissue or fluid sample. We applied the BRiSK technique to the analysis of aqueous or vitreous tap specimens from 10 cases of endophthalmitis (4 post-cataract extraction, 2 post-intravitreal injection, 1 bleb-associated, 1 endogenous, 2 other post-surgical). Informed consent was obtained for all patients and a minimum of 0.1 ml of the aqueous or vitreous tap specimen was submitted for standard microbiological cultures. The BRiSK analysis was then compared with the culture results.

Results: : The BRiSK analysis was strongly positive for foreign (non-human) DNA in four samples, confirming the microbiological culture results in these cases by identifying coagulase negative staphylococcus (2), streptococcal species (1), and beta-hemolytic streptococcus (1). BRiSK analysis was negative in two cases of culture negative endophthalmitis and inconclusive in four other cases of endophthalmitis. BRiSK also identified the Torque Teno virus, a common virus unlikely to cause disease, in multiple samples.

Conclusions: : BRiSK represents a novel method of identifying both bacterial and viral species from aqueous and vitreous tap specimens from eyes with endophthalmitis. The application of BRiSK to a larger number of samples should provide new insights into cases of culture negative endophthalmitis.

Keywords: endophthalmitis