Molecular Characterization and Antifungal Susceptibility of Oral <i>Candida</i> Biome in Children

Abstract

Background: Candida species are established members of the oral microbiota, and asymptomatic carriage is commonly observed in healthy populations. Objectives: This study aimed to molecularly identify Candida species isolated from the oral cavities of children referred to Shafizadeh Amir Kola Hospital in Babol, Iran, and to evaluate their antifungal susceptibility profiles. Methods: Samples were collected using sterile swabs and transferred to the mycology laboratory. Candida species were identified using phenotypic (CHROMagar) and molecular methods. The antifungal susceptibility of the isolates to amphotericin B, fluconazole, and nystatin was evaluated according to Clinical and Laboratory Standards Institute (CLSI) M27-A3 guidelines. Results: Of the 200 samples, 46 (23%) were positive by direct microscopy and culture. CHROMagar results, based on colony color, showed 35 colonies (76%) that were green, 7 (15%) that were cream to pink, 3 (6.5%) that were pink to lavender, and 1 (2.5%) that was blue. Digestion of the PCR products with MspI enabled discrimination among medically important Candida species, including 35 isolates (76.1%) of C. albicans, 7 (15%) of C. parapsilosis, 1 (2.2%) of C. glabrata, 1 (2.2%) of C. tropicalis, 1 (2.2%) of C. krusei, and 1 (2.2%) of Clavispora lusitaniae (formerly C. lusitaniae). Based on geometric mean values, the most effective drugs against Candida isolates were amphotericin B (0.016 µg/mL) and nystatin (0.194 µg/mL). Fluconazole resistance was observed in 3 isolates with a minimum inhibitory concentration (MIC) ≥ 8 µg/mL. Conclusions: C. albicans remains the predominant species in the oral Candida microbiota, although emerging and less common species have also been reported. Therefore, accurate species identification and assessment of antifungal susceptibility may play an important role in guiding treatment and preventing oral candidiasis.