Abstract / Summary
Abstract Background Enterobacter hormaechei is a member of the Enterobacter cloacae complex and an emerging multidrug-resistant opportunistic pathogen. Enterobacter endophthalmitis is uncommon and usually aggressive; an indolent postoperative presentation associated with species-level detection of E. hormaechei has not been well characterized. Case presentation: A 68-year-old woman with previous central retinal vein occlusion and retinal laser photocoagulation underwent left cataract surgery. Approximately 1 month later, after postoperative drops had been stopped, she developed ocular symptoms diagnosed as conjunctivitis. Follow-up was irregular, and she re-presented approximately 4 months later with persistent visual loss. At admission, left visual acuity was 0.08 (decimal), intraocular pressure was 13 mmHg, the conjunctiva and anterior chamber were quiet, the intraocular lens was centered, and vitreous opacity was most marked anteriorly. Vitreous DNA metagenomic next-generation sequencing (mNGS) detected E. hormaechei (656 reads; relative abundance, 2.80%); the laboratory categorized the signal as a low-attention finding. Intravitreal ceftazidime (1.0 mg/0.1 mL) and norvancomycin hydrochloride (1.0 mg/0.1 mL) produced no clear improvement after 1 week. Pars plana vitrectomy with silicone-oil tamponade was then performed. At 2 months, the retina was attached, intraocular inflammation was controlled, and best-corrected visual acuity was 0.12 (decimal); residual visual limitation was confounded by ischemic retinal disease. Conclusion Delayed postoperative endophthalmitis may present with little anterior-segment inflammation. Vitreous mNGS can identify unexpected organisms, but a low-abundance result without orthogonal confirmation should be interpreted as supportive rather than definitive evidence of causation. Persistent vitreous opacity despite intravitreal antibiotics may justify vitrectomy for source control, diagnostic sampling, and media clearance.