Distribution of fungal isolates recovered from clinical specimens in Saudi Arabia: A four-year retrospective study.

BACKGROUND: Fungal infections are a growing clinical concern, especially among immunocompromised patients. Local data on fungal isolates remain limited in Saudi Arabia. This study described the annual distribution of major fungal groups and the overall species-level distribution of fungal isolates recovered from clinical specimens at a tertiary center. METHODS: A retrospective analysis was conducted on clinical specimens submitted for fungal culture between 2021 and 2024 at a central mycology laboratory in Riyadh, Saudi Arabia. Blood culture isolates were excluded because they follow a separate diagnostic workflow and are referred to the mycology laboratory only after a positive result. Isolates were identified using conventional methods and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Annual distribution was assessed at the level of major fungal groups (Candida species, filamentous fungi, non-Candida yeasts and yeast-like fungi). Genus and species-level distributions are reported as cumulative totals throughout the study period. RESULTS: Of 7443 specimens processed, 1658 (22%) yielded fungal growth. Candida spp. were the most frequently identified isolates (64.3%), followed by filamentous fungi (27.1%), then non-Candida yeasts and yeast-like fungi (8.6%). The predominant Candida spp. were Candida albicans (39.7%), Nakaseomyces glabratus (formerly C. glabrata) (14.7%), C. dubliniensis (12.5%), C. tropicalis (10.0%), C. parapsilosis (9.7%), and Candidozyma auris (formerly C. auris) (5.8%). Among filamentous fungi, Aspergillus spp. constituted the largest group (43.9%), followed by dermatophytes (37.4%). The predominant species were A. flavus (18.9%), A. niger (16.5%), Microsporum canis (25.8%), and the Trichophyton mentagrophytes/interdigitale complex (7.8%). Isolate distributions varied by specimen type, with the highest numbers recovered from patients aged ≥ 65 years. CONCLUSIONS: This four-year study described the distribution of fungal isolates in a Saudi healthcare setting. Candida spp. were the predominant fungal isolates overall, with C. albicans being the most frequently recovered species, while Aspergillus spp. represented the predominant filamentous fungal group.