CLINICAL UTILITY OF BETA-D-GLUCAN TESTING FOR ENDOGENOUS FUNGAL CHORIORETINITIS OR ENDOPHTHALMITIS

Purpose: To evaluate serum beta-D-glucan (BDG) as a biomarker for endogenous fungal eye infection. Methods: Retrospective case–control study of 88 patients with a BDG test and eye examination at UPenn (2013–2018). Cases had endogenous fungal chorioretinitis or endophthalmitis diagnosed by eye examination and confirmed with positive culture; controls were without these fungal eye findings. Charts were reviewed for BDG values, blood/vitreous cultures, and eye examinations. Outcomes were BDG sensitivity, specificity, positive predictive value, and negative predictive value for fungal chorioretinitis or endophthalmitis, using prespecified BDG cut-off points of ≥80, ≥250, and ≥500 pg/mL as test positive. Results: Cases included six chorioretinitis and four endophthalmitis patients. Controls included 78 patients without chorioretinitis or endophthalmitis. Defining BDG ≥80 pg/mL as test positive, the BDG sensitivity (95% confidence interval) was 66.7% (22.3%–95.7%) for chorioretinitis and 100% (39.8%–100%) for endophthalmitis. The specificity was 74.4% (63.2%–83.6%) when BDG values ≥80 pg/mL were test positive, and 85.9% (76.2%–92.7%) when values ≥250 pg/mL were test positive. For a 1% endophthalmitis prevalence and BDG cut-off value of ≥80 pg/mL, the positive predictive value was 3.8% (2.4%–5.2%) and negative predictive value was 100% (99.1%–100%). Conclusion: For endogenous fungal endophthalmitis, BDG's sensitivity and specificity seem good and the negative predictive value is high; a larger ophthalmic study is indicated.