P-1732. Antifungal Susceptibility Patterns of Major Candida Species Isolated From 1390 Bloodstream Infections in Costa Rica: A 12-Year Experience

Abstract Background Candida species represent 80% of nosocomial fungal infections, with candidemia being the most frequent invasive disease. In Latin America, Candida resistance is generally low, but information from Central America is scarce. We aimed to describe antifungal susceptibility of Candida species isolated from bloodstream infections at two national adult hospitals in Costa Rica from 2012 to 2023. Methods This retrospective study analyzed the first isolate from candidemia episodes caused by C. albicans, C. tropicalis, C. parapsilosis, and C. glabrata with available susceptibility results. Testing used VITEK 2 system. Interpretation followed CLSI M27M44S-Ed3 guidelines. Amphotericin B susceptibility was defined as MIC ≤1μg/ml. Differences between species were assessed using Fisher's exact test, and temporal trends with chi-square test. Results We analyzed 1,390 isolates: C. parapsilosis 689 (49.6%), C. albicans 448 (32.2%), C. tropicalis 131 (9.4%), and C. glabrata 122 (8.8%). Fluconazole susceptibility was high in C. albicans (97.1%) and C. tropicalis (96.2%), but lower in C. parapsilosis (40.6%, p< 0.001). C. glabrata isolates were predominantly susceptible-dose dependent (96.1%). Voriconazole showed high activity against C. albicans (98.7%) and C. tropicalis (96.9%), but resistance in C. parapsilosis (20.2%). Amphotericin B maintained excellent activity against all species (98.7% overall). Echinocandins demonstrated high efficacy against C. albicans, C. tropicalis, and C. parapsilosis (≥99%), but reduced activity against C. glabrata (caspofungin 41.3% susceptible, micafungin with 70.6% intermediate and 29.4% resistant). No significant temporal trends in susceptibility were observed over the 12-year period. Conclusion Our findings reveal significant azole resistance in C. parapsilosis, particularly to fluconazole (59.4%) and voriconazole (20.2%). Amphotericin B maintains excellent activity against all species. Echinocandins remain highly effective against most Candida species except C. glabrata. These patterns have important implications for empirical antifungal therapy selection in our region. Disclosures All Authors: No reported disclosures