Comparison of the effect of garlic extract and gentamicin on icaA biofilm gene expression in Staphylococcus aureus

In this study the effect of garlic extract and its comparison with gentamicin antibiotic on three strains of S. aureus bacteria was evaluated based on antibiogram method and MIC test, the results of which confirm the anti-staphylococcal effect of garlic extract and its synergistic effect with gentamicin antibiotic. Based on phenotypic test, the effect of garlic extract and gentamicin alone and together on reducing the production of biofilm in this bacterium was evaluated and proven. The presence of icaA gene in the studied strains was confirmed by PCR and using Real time PCR technique, the expression of icaA gene under the treatment of garlic extract, gentamicin and the combined treatment of garlic and gentamicin compared to the untreated samples was studied. For the standard strain, gentamicin and garlic extract reduced icaA gene expression by 59% and 64%, respectively, and combined use of these two substances reduced the expression of this gene by about 25% compared to the control sample. In other words, it led to a 75% reduction in the expression of this gene. In the case of pathogenic strains, these treatments also showed a significant effect on reducing icaA expression, so that the simultaneous use of garlic extract and gentamicin could reduce the expression of this gene to 11% of the untreated sample. In other words, it leads to an 89% reduction in icaA expression. The results of all these tests showed the favorable effect of garlic extract against S. aureus.