Inhibitory Effect of Probiotic Yeast Saccharomyces cerevisiae on Biofilm Formation and Expression of α-Hemolysin and Enterotoxin A Genes of Staphylococcus aureus

Introduction and Objectives: Staphylococcus aureus as an opportunistic pathogen is the cause of a variety of diseases from mild skin infections to severe invasive infections and food poisoning. Increasing antibiotic resistance in S. aureus isolates has become a major threat to public health. The use of compounds produced by probiotics can be a solution to this problem. The purpose of this study was to investigate the effect of Saccharomyces cerevisiae on some virulence factors (biofilm, α-hemolysin and enterotoxin A) of S. aureus. Materials and Methods: Supernatant and lysate extracts were prepared from S. cerevisiae S3 culture. Sub-MIC concentrations of both extracts were separately applied to S. aureus ATCC 29213 (methicillin-sensitive Staphylococcus aureus; MSSA) and S. aureus ATCC 33591 (methicillin-resistant Staphylococcus aureus; MRSA) strains. Biofilm formation of these strains was measured by microtiter plate assay and expression level of α-hemolysin and enterotoxin A genes (hla and sea, respectively) using real-time PCR technique. Results: The supernatant extract has reduced both biofilm formation and expression of sea and hla genes, while lysate extract only had anti-biofilm effects. In all tests, the MRSA strain has shown more susceptibility to yeast extracts than MSSA strain. Conclusion: The current study has exhibited the favorable antagonistic effects of S. cerevisiae S3 as probiotic yeast on the MSSA and the MRSA strains. By conducting further studies, the compounds produced by this yeast can be used to control S. aureus infections.

Keywords:

Biofilm , Exotoxins , Probiotic , Saccharomyces cerevisiae , Staphylococcus aureus