Metagenomic next-generation sequencing of aqueous humor guides targeted therapy for Staphylococcus epidermidis endophthalmitis in chronic ocular graft-versus-host disease: a case report

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Purpose To report a case of Staphylococcus epidermidis endophthalmitis in chronic ocular graft-versus-host disease, refractory to empirical broad-spectrum antibiotics, rapidly identified by metagenomic next-generation sequencing of aqueous humor, and successfully managed with targeted vancomycin without vitrectomy. Methods Case report. Results A 35-year-old male with chronic oGVHD following allo-HSCT for acute myeloid leukemia developed endophthalmitis after 10 months of progressive disease. Slit-lamp examination revealed central corneal ulceration (4 × 2 mm) with hypopyon (1 mm). B-scan ultrasonography confirmed mild vitreous haze. Conventional microbiological workup of aqueous humor—including Gram stain, potassium hydroxide (KOH) mount, and bacterial/fungal culture—yielded negative results. Aqueous humor mNGS detected 5,543 unique reads of S. epidermidis (genome coverage 12.3%, no co-pathogens), exceeding the clinical significance threshold. Based on this result, therapy was switched to targeted intracameral and periocular vancomycin (10 mg/ml) combined with intravenous vancomycin (0.5 g twice daily). Vancomycin was selected for its reliable Gram-positive coverage, including coagulase-negative staphylococci , referencing the established intravitreal dose of 1 mg/0.1 mL. The infection was controlled without corneal perforation or vitrectomy. AMT was performed for persistent epithelial defects. At 1.5 years follow-up, anatomical preservation was maintained (BCVA 20/400 OD; 20/40 OS). Conclusion In immunosuppressed oGVHD patients with suspected endophthalmitis, aqueous humor mNGS overcomes the diagnostic limitations of conventional culture and guides a timely switch from empirical antibiotics to targeted therapy, achieving infection control and anatomical preservation without invasive vitrectomy or enucleation.