Inhibition of staphylococcal biofilm-related gene transcription by rhodomyrtone, a new antibacterial agent

Abstract

Biofilms are one of the most important staphylococcal virulence factors, which are often associated with antibiotic resistance in the organisms. Our previous studies have demonstrated that rhodomyrtone from Rhodomyrtus tomentosa leaves exerts the activity against biofilm-forming staphylococci. In this study, we further evaluated the efficacy of the compound on transcription of biofilm-related genes including atl and ica, as well as their products in representative biofilm-forming strains Staphylococcus aureus SA113 and Staphylococcus epidermidis O47. Minimal inhibitory concentration of rhodomyrtone against S. aureus and S. epidermidis was 0.5 μg/mL. The transcription of biofilm-related genes was investigated using Northern blot analysis. Reduction in atl and ica transcription signals following rhodomyrtone treatment was observed. A different autolysin profile was detected in the rhodomyrtone-treated cells with respect to the untreated ones. In contrast, no differences in the production of polysaccharide intercellular adhesin, encoded by ica, of rhodomyrtone-treated and the untreated cells were observed.