Effect of Saccharomyces boulardii Extract on SAP2 Gene Expression and Antifungal Susceptibility of Candida albicans

Saccharomyces boulardii, a non-pathogenic yeast, is effective on prevention and treatment of intestinal infections caused by bacterial pathogens and also affects the virulence factors of Candida albicans. SAP2, an important potential virulence factor of C. albicans is a suitable target for a new research.
The current study aimed at investigating the effect of S. boulardii extract on the expression of SAP2 gene and antifungal susceptibility of C. albicans isolates.
The current study investigated SAP2 relative expression and antifungal susceptibility patterns of C. albicans species isolated from oral lesions of HIV patients and the standard strain ATCC 10231 after exposure to S. boulardii extract. Susceptibility of C. albicans isolates to antifungal drugs was assessed according to those proposed in the clinical and laboratory standards institute (CLSI) M44-A2 reference method. The real-time polymerase chain reaction (PCR) was performed to evaluate SAP2 gene expression.
Saccharomyces boulardii extract 0.48 mg/mL changed the antifungal susceptibility pattern of C. albicans isolates to ketoconazole and itraconazole. Before exposure, 53.3% of the isolates were sensitive to ketoconazole, while it increased to 73.3% after exposure to S. boulardii extract. The sensitivity to itraconazole increased from 6.7% to 26.7% after exposure to S. boulardii extract. Although susceptibility of C. albicans isolates to other antibiotics (fluconazole, clotrimazole, nystatin, and amphotericin-B) did not change after exposure to S. boulardii extract, there was a significant difference in the average inhibitory zones of the isolates after exposure to S. boulardii extract.
The level of SAP2 expression significantly reduced in the isolates treated with 0.48 mg/mL S. boulardii extract. Comparison of SAP2 gene expression between ketoconazole-resistant and -intermediate isolates, and the ketoconazole-sensitive ones demonstrated the relative higher gene expression in resistant and intermediate isolates. Saccharomyces boulardii extract can be considered as a suitable probiotic candidate to prevent and treat C. albicans infections.