Abstract
Purpose :
Bacterial endophthalmitis is one of the worst complications after cataract surgery or intravitreal anti-VEGF (Vascular Endothelial Growth Factor) injections. Immediate treatment with intravitreal antibiotics would benefit the outcome, but is hampered by the need to take a vitreous biopsy for bacterial growth assessment in specialized hospitals. This costs precious hours, because antibiotics can only be administered after the taking of a biopsy since antibiotics will inhibit the culture of bacteria. New diagnostic options for detection of bacterial species in vitreous samples that are already treated with antibiotics hours before the biopsy, would overcome this problem. The aim of this study is to analyse the correlation of a molecular bacterial detection method with classical culture outcomes. The molecular method is a pan-bacterial 16S microbiome approach with Next Generation Sequencing that is able to detect all bacterial species. The ultimate goal is to formulate a new treatment strategy for endophthalmitis using antibiotics directly at presentation followed by biopsy and diagnosis.
Methods :
Vitreous samples of 65 endophthalmitis patients with known culture results from our biobank were re-analysed using a newly developed micelle (mic)PCR technique for bacterial 16S rRNA gene. The micPCR allows more accurate detection of pathogens than other PCR-based techniques by differentiating true signals from contamination. Bacterial culture outcomes were retrieved from medical records of patients. Genus outcomes from the micPCR were compared to culture outcomes.
Results :
With the pan-bacterial micPCR 62% of biopsies were positive for bacterial DNA, compared to 77% for bacterial culture. The correlation on genus level between micPCR and culture was 75%. The micPCR of bacterial DNA showed more specificity, but slightly less sensitivity than bacterial culture.
Conclusions :
We consider the correlation between the culture and pan-bacterial PCR-testing as acceptable and promising. The lower sensitivity of the micPCR-testing may be attributed to long storage as the micPCR was done months to years after the initial culturing. The shortening of treatment delay might improve clinical outcome of endophthalmitis treatment.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.