Antagonistic Interactions of “Ya-Sa-Marn-Phlae” Ethanol Extract in Combination with Topical Antiseptics against Clinical Isolates ofStaphylococcus aureus

Abstract

This investigation was aimed at assessing a possible interaction of a traditional Thai herbal recipe, “Ya-Sa-Marn-Phlae (YSMP),” used for wound treatments with topical antiseptics, povidone-iodine (PI) solution and hydrogen peroxide (H2O2), and effects of THR-SK010 alone and the combinations onStaphylococcus aureus. Antibacterial activities of ethanol extracts from the herbal recipe were determined against both methicillin resistantStaphylococcus aureus(MRSA) and methicillin-susceptibleS. aureus(MSSA). YSMP exhibited remarkable antistaphylococcal activity with MIC values of 3.9–7.8 μg/mL. This recipe possessed bacteriostatic activity and did not reduce the tolerance of both MRSA and MSSA isolates to the high ionic strength. Interaction between THR-SK010 and the antiseptics was carried out by checkerboard testing and time-kill assay. Both indifferent and slightly antagonistic effects were observed with THR-SK010/PI and THR-SK010/H2O2combinations against the tested isolates. In addition to commercially available antiseptics, THR-SK010 offered additional therapeutic options for the decolonization of MRSA and MSSA. Topical application of plant extracts with antioxidant activity, such as THR-SK010, should not be used immediately with PI or H2O2and further investigation on this interaction is needed.