Aram Sharifi, Abdolmajid Mohammadzadeh, Pezhman Mahmoodi, Taghi Zahraei Salehi,
Volume 20, Issue 3 (7-2026)
Background: Biofilm formation in Staphylococcus aureus (S. aureus), mediated by the ica operon, is a key virulence factor. This study examined how different glucose-supplemented broth culture media influence biofilm production and ica gene expression in S. aureus.
Methods: The phenotypic ability to adhere to a polystyrene surface and produce a slime layer was evaluated using the microtiter plate test (MtP) and Congo red tube test, respectively. Using PCR, the presence of the intercellular adhesion (ica) locus in S. aureus strains was confirmed. Subsequently, quantitative real-time RT-PCR was performed to investigate icaA transcription in various media, including tryptic soy broth (TSB), brain-heart infusion broth (BHIB), nutrient broth (NB), and Mueller-Hinton broth (MHB), containing 0, 0.25, 0.5, 1, and 2% glucose.
Results: Our results showed that although all studied strains adhered to the wells of polystyrene microtiter plates, the optimal rate of biofilm formation was observed in TSB medium containing 1% glucose. However, biofilm formation was not significantly different in NB, MHB, and BHIB media. Supplementation of all media with 1% glucose resulted in the highest biofilm production, and icaA transcription increased in all media after glucose addition up to 1%.
Conclusion: The results of the present study indicated that TSB medium supplemented with 1% glucose was the most appropriate medium for evaluating biofilm formation by S. aureus isolates.
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