Unveiling the impact of selected essential oils on MRSA strain ATCC 33591: antibacterial efficiency, biofilm disruption, and staphyloxanthin inhibition.

This work aimed to evaluate the effects of 4 selected essential oils on planktonic cells and microbial biofilms of the Staphylococcus aureus strain (MRSA ATCC 33591). The antibacterial activities of the four essential oils Geranium (Pelargonium graveolens), PgEO, Tea Tree (Melaleuca alternifolia) MaEO, Lemon peel (Citrus limon) ClEO and Peppermint (Mentha piperita) MpEO had MICs ranging from 1.56 to 12.5 µl/ml. The evaluation of the antibiofilm activities of the 4 EOs revealed that they had antiadhesive activities against S. aureus MRSA biofilms; the activity reached 60% (the EO of MpEO peppermint at a concentration of 3.12 µl/ml), and the eradication activity was 80% (the EO of PgEO and MpEO at 3.12 µl/ml). The antibiofilm activity of S. aureus has been explained by the binding of several essential oil bioactive molecules to the SarA protein, the main target protein involved in biofilm formation. The synthesis of the virulence factor staphyloxanthin by S. aureus MRSA ATCC 33591 was significantly inhibited in the presence of PgEO at a concentration of MIC/2. This inhibition was explained by the binding of the main PgEO molecules (β-citronellol and geraniol) to the CrTM protein involved in the staphyloxanthin synthesis pathway. There is evidence that these essential oils could be used as potential anti-virulents to control Staphylococcus biofilm formation.