Microbial Characteristics and Etiologic Patterns of Endophthalmitis at a Tertiary Referral Center: A Retrospective Cohort Study.

Introduction: Endophthalmitis is a serious vision-threatening intraocular infection. Its etiology, microbiologic profile, and anti-microbial resistance patterns vary by region. Understanding local patterns is essential for guiding empiric therapy and improving patient outcomes. Authors of this study aimed to identify the most common etiologies, causative organisms, and resistance patterns of endophthalmitis at a Midwestern tertiary referral center. Methods: Authors conducted a retrospective chart review of patients diagnosed and treated for infectious endophthalmitis at the University of Kansas between 2008 and 2022. Adult patients with infectious endophthalmitis who underwent vitreous biopsy with microbiologic testing were included. Clinical findings, microbiology results, anti-microbial resistance patterns, empiric treatment regimens, and patient characteristics were collected and analyzed. Results: A total of 149 patients met the inclusion criteria, of whom 52 had positive microbiologic cultures, yielding 64 microbial isolates. The most common etiologies were endogenous infection (n = 43), postoperative infection (n = 32), infection secondary to corneal ulcer (n = 19), and trauma (n = 14). Among culture-positive cases, most isolates were bacterial (61/64). Conclusions: Endogenous infection was the most common cause of endophthalmitis in this Midwestern cohort. Regional variation in causative organisms and antimicrobial resistance patterns highlights the importance of local surveillance and tailored empiric treatment strategies to optimize patient outcomes.