Trends in pathogens causing microbial keratitis in studies conducted in Mexico: a 38-year literature review

Purpose: To review the available literature, including peer-reviewed publications and grey literature, describing the microorganisms and demographic characteristics reported in studies of non-viral microbial keratitis conducted in Mexico. Methods: A comprehensive literature search was conducted on March 10, 2026, using databases including PubMed, Scopus and SciELO. To incorporate grey literature, non-traditional sources such as Google Scholar, ResearchGate, and thesis repositories from ophthalmology training institutions—Universidad Nacional Autónoma de México, Universidad Autónoma de Nuevo León, Tecnológico de Monterrey, and Universidad de Monterrey—were also included. Results: We identified 48 studies on infectious keratitis in Mexico (1988–2026), including 14,651 patients. Bacterial keratitis was the most frequent form; gram-positive cocci, especially Staphylococcus epidermidis and Staphylococcus aureus, predominated, whereas Pseudomonas aeruginosa was the leading gram-negative pathogen, particularly among contact lens wearers, with higher frequencies reported in Monterrey and Guadalajara than in Mexico City. Fungal keratitis, reported in 1,446 patients, was mainly caused by Fusarium spp., Aspergillus spp., and Candida albicans, with several dematiaceous fungi also described. Acanthamoeba keratitis was rare (0.3% of infectious keratitis), with only 13 cases reported. Culture positivity and age distribution varied widely across studies. Overall, the reviewed studies show substantial regional heterogeneity with a predominance of gram-positive bacterial pathogens. Conclusions: In the reviewed studies from Mexico, reported non-viral infectious keratitis cases were most commonly caused by bacteria, particularly gram-positive organisms. Among contact lens wearers, gram-negative bacteria are more frequently isolated. The prevalence of fungal and Acanthamoeba-related keratitis in the available literature appears to align with global trends.