Abstract
Purpose :
Exogenous endophthalmitis remains a dreaded complication of intraocular surgery or trauma. To overcome the high percentage of culture-negative endophthalmitis, various molecular techniques have been used to improve the aetiological diagnosis. Nanopore-targeted sequencing (NTS) technology is emerging as a cost-effective and user-friendly platform for real-time detection of pathogens in clinical samples. Here, we investigated the utility of metagenomic 16S rRNA NTS in identifying the bacterial pathogens causing exogenous endophthalmitis.
Methods :
NTS was carried out in vitreous fluids (VF) from 42 patients with exogenous endophthalmitis (27 post-traumatic, 15 post-operative) and compared with conventional diagnostic methods. Positive bacterial cultures were identified using the VITEK-2 automated ID system (Biomerieux, France). For NTS, DNA was extracted from VF and 16SrRNA gene PCR for bacteria was performed, followed by nanopore amplicon sequencing. The generated reads were analyzed in real-time using EPI2ME data analysis platform (Oxford Nanopore Technologies, UK). 30 VF from patients undergoing surgery for non-infectious retinal disorders were used as controls.
Results :
Culture-based diagnosis of bacteria was achieved in 19/42 (45.2%) VF. NTS results displayed a strong match with culture results in 17/19 (89.5%) VF, among which 5 VF showed polybacterial etiology only by NTS. However, 2/19 (11.5%) VF showed poor correlation between NTS and culture. Among the culture-negative VF, NTS detected bacteria in 8/20 (40%) VF (Single etiology 6, polybacterial etiology 2). Overall, NTS increased the bacterial detection rate by 20% over traditional culture. None of the 30 control VF as well as 3 VF culture positive for fungi detected any bacteria by NTS. The bacterial agents revealed only by NTS ranged from common ocular pathogens including species of Staphylococcus, Streptococcus, Clostridium, Hemophilus and Bacillus to rare/unreported ocular pathogens including species of Exiguobacterium, Gemella, Cloacibacterium, Erwinia and Chryseomicrobium.
Conclusions :
With NTS showing a higher positivity rate than culture methods to detect bacteria in VF, the platform holds tremendous potential as a user-friendly, sensitive, rapid and cost-effective technique complementary to conventional methods to diagnose infective endophthalmitis.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.