Long-term Infectious Keratitis Microbiology and Resistance Patterns With Forecasts to 2030: A 23-Year Analysis

To analyze 23-year trends in microbiology and antibiotic resistance among infectious keratitis (IK) isolates at a tertiary center in Mexico City and to generate validated forecasts through 2030 to inform empiric therapy and stewardship.

Corneal scrapings were processed using standardized sampling, culture, and identification protocols; susceptibilities were interpreted per CLSI (VITEK and Kirby-Bauer). Annual Chow tests (2004-2022; ≥3 data points per side) screened for structural breaks in organism prevalence and resistance, and linear regression summarized long-term trends (2002-2024). For forecasting, each microorganism and antibiotic series was modeled as a univariate time series using Historical Mean, linear and quadratic OLS, ETS, and ARIMA (fit on logit-transformed percentages with drift). ARIMA orders were chosen by rolling-origin cross-validation (training 2002-2018). Final model selection was based on lowest MAE on the validation period (2019-2024), and 2025 to 2030 forecasts with 95% CIs were produced from the selected model.

Among 4748 cultures, 2918 (61.46%) were positive: bacteria 2624 (89.92%) and fungi 294 (10.08%). Bacterial isolates were 81.44% Gram+ and 18.56% Gram-. The leading organisms were Staphylococcus epidermidis, other Gram+, other coagulase-negative staphylococci, Pseudomonas aeruginosa, and Staphylococcus aureus; Fusarium dominated fungi (52.38%). Structural breaks clustered in 2005 to 2012; positive-culture rates rose from ∼35 to 50% pre-2010 to ∼80%, with few new structural breaks after 2020. Gram+ resistance declined in β-lactams/50S agents but increased for fluoroquinolones, vancomycin, and gentamicin. Gram- resistance rose in cephalosporins/carbapenems, while nitrofurantoin decreased; Gram- showed no consistent long-term trend. Historical Mean often minimized MAE; ARIMA/regression/ETS performed best with persistence, curvature, or fluctuations. Forecasts to 2030 indicate broad stabilization, with watchpoints in Gram+ vancomycin/30S agents and Gram-cephalosporin/carbapenem classes; positive rates remain high and negatives decline.

Infectious keratitis microbiology underwent a late-2000s reconfiguration followed by durable stabilization. Forecasts project continued stability with targeted resistance signals, supporting ongoing local surveillance, antimicrobial stewardship, and optimized diagnostic practices.