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

Table 1

Fractional inhibitory concentration indices (FIC) of antimicrobial agents determined by a two-dimensional chequerboard assay against methicillin resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus (MSSA), and S. aureus ATCC 29213^a when combined with an effective herbal formula, THR-SK010E, and topical antiseptics (povidone-iodine; PI and hydrogen peroxide; H₂O₂).

Antibacterial agents	ΣFIC ranges	Percentage of the tested isolated
		Synergy	Indifference	Antagonism
		ΣFIC ≤ 0.5	0.5 < ΣFIC ≤ 4	ΣFIC > 4
THR-SK010/PI
MRSA (𝑛=5)	5.00–9.00			100
MSSA (𝑛=5)	2.00–5.00		80	20
THR-SK010/H2O2
MRSA (𝑛=5)	1.05–2.53		100
MSSA (𝑛=5)	0.51–2.14		100

^aΣFIC indices of pared combinations of THR-SK010 and povidone-iodine and THR-SK010 and H₂O₂ against S. aureus ATCC 29213 were 3.00 and 1.06, respectively.