Predictors of Infectious Corneal Ulcer Outcomes in a Real-World Cohort: Clinical Risk Factors, Microbiology, and...

To characterize the epidemiology, microbiological spectrum, and antimicrobial resistance of infectious corneal ulcers in a Northern Portugal referral center and to identify predictors of severe structural outcomes in real-world practice.

Retrospective observational cohort study of consecutive infectious corneal ulcer episodes undergoing microbiological sampling (2014-2025). Baseline demographics, ocular and systemic risk factors, clinical severity markers (ulcer location, hypopyon), microbiologic results, organism groups, antimicrobial susceptibility and initial empiric therapy were recorded. The primary outcome was severe structural failure (corneal perforation and/or evisceration). Secondary outcomes included central corneal scarring and hospitalization. Descriptive microbiological endpoints included culture positivity, pathogen distribution, and antimicrobial susceptibility patterns. Predictors of severe outcome were assessed using multivariable logistic regression.

The study included 206 episodes (205 patients; mean age 54.6 ± 20.7 years). Microbiologic confirmation was obtained in 49.0% of episodes. Among microbiologically confirmed episodes, bacterial keratitis predominated (76.2%), followed by other/unspecified organisms (13.9%), polymicrobial infections (5.9%), and fungal keratitis (4.0%). The most frequent identified pathogens included Pseudomonas aeruginosa and Cutibacterium acnes, alongside PCR-detected HSV-1, coagulase-negative staphylococci, and Corynebacterium spp. Resistance was uncommon among isolates with available susceptibility data (fluoroquinolone 12%, aminoglycoside 9.1%, cephalosporin 5.9%); MDR occurred in 4.7%. Severe outcome occurred in 8.4% of episodes with available data. In multivariable analysis, hypopyon (aOR 6.85), systemic immunosuppression (aOR 4.89), and diabetes mellitus (aOR 2.50) independently predicted severe outcome.

In this cohort, severe corneal ulcer outcomes were primarily driven by baseline inflammatory severity and host vulnerability (hypopyon, immunosuppression, diabetes), while antimicrobial resistance and MDR were infrequent. Early risk stratification using these clinical and systemic factors may guide escalation and monitoring, alongside ongoing local resistance surveillance.