Two-Decade Retrospective Analysis of Endogenous Endophthalmitis in Spain and Mexico: A Comprehensive Study

<b>Objectives:</b> The aim of this study was to investigate endogenous endophthalmitis (EE) in Spain and Mexico, focusing on microbial patterns, antibiotic resistance, infection sources, risk factors, and patient outcomes. <b>Methods:</b> Over 20 years, 705 endophthalmitis cases were reviewed, and we identified 78 cases of EE in Santiago de Compostela, Spain, and Mexico City, Mexico. Microbial etiology, infection sources, antibiotic resistance, and treatment outcomes were compared between patients from Spain and Mexico. <b>Results:</b> Among the 78 EE cases, 47 (60.25%) were from Spain and primarily had bacterial infections (57.1%, mainly Staphylococcus and Streptococcus). In contrast, 31 cases (39.74%) were from Mexico and had a higher prevalence of fungal infections, particularly Candida (47.1%). Diabetes mellitus was a significant risk factor, and was more common in Mexico (61.3%) than in Spain (37.0%). The Spanish cohort exhibited notable antibiotic resistance, especially in Staphylococcus. Treatment typically involved systemic and intraocular antibiotics, with vitrectomy performed in 61.5% cases. Post-treatment, bacterial infections had higher success rates (approximately 50%) compared with fungal infections (approximately 30%). Evisceration was necessary in 9% cases, and the overall mortality rate was approximately 4.4%; it was slightly higher in Mexico than in Spain. <b>Conclusions:</b> The study highlights significant regional differences in EE between Spain and Mexico, particularly regarding microbial etiology and antibiotic resistance. The findings emphasize the need to adapt healthcare practices to specific regions to improve EE treatment outcomes, underscoring the importance of ongoing research and interregional collaboration to better understand and manage this complex condition.