Purpose: The purpose of this study was to report the clinical etiologies, microbial spectrum, antibiotic resistance, and visual acuity (VA) outcomes associated with acute endophthalmitis. Methods: A retrospective chart review of patients with International Classification of Diseases (ICD)-9 and ICD-10 codes for endophthalmitis over a 6-year period (2011-2016) at a tertiary referral center was performed. The clinical records were reviewed to evaluate clinical etiologies, microbial spectrum, antibiotic susceptibilities and resistance, and visual outcomes. Results: Medical records of 94 patients treated for culture-proven endophthalmitis were reviewed. The etiologies of endophthalmitis were exogenous in 68.8% of cases and endogenous in 31.2% of cases. The most common inciting factors for exogenous endophthalmitis were progression of corneal ulcer and postoperative infection after cataract extraction. The microbial spectrum of causative organisms was dominated by coagulase-negative Staphylococcus (30.9%), followed by Staphylococcus aureus (23.4%). The most frequent fungal isolates were Candida species. Antibiotic susceptibilities of gram-positive bacteria ranged from 96.7% for vancomycin to 28.8% for penicillin G. Antibiotic susceptibilities of gram-negative bacteria were overall very high, with >90% susceptibility among isolated culture samples. Final VA outcomes of 20/400 or better were reported in 62.5% of patients. Conclusions: The study demonstrates that the most frequent clinical etiology of endophthalmitis was exogenous due to progression of corneal ulcer and postoperative infection after cataract extraction. The spectrum of pathogens causing endophthalmitis is composed of mainly Gram-positive organisms (particularly coagulase-negative Staphylococcus). VA was improved in the majority of patients after treatment for endophthalmitis.
Keywords: acute endophthalmitis; antibiotic resistance; microbial spectrum.