MRSA is known to produce organic acids through carbohydrate metabolism pathways [10, 11]. Acetic acid is the main organic acid produced by MRSA, which lowers pH in the infected area; this lowered pH facilitates biofilm formation by microorganisms [10]. Our results showed that the ethanol extract of A. princeps inhibited the pH reduction induced by MRSA. This result indicates that the ethanol extract of A. princeps inhibits carbohydrate metabolism in MRSA.