Combination of Acacetin with Antibiotics against Methicillin Resistant Staphylococcus aureus Isolated from Clinical Specimens

Methicillin-restitant Staphylococcus aureus (MRSA) is very dangerous bacteria and one of the most feared nosocomial germs. In this study, acacetin was evaluated against 20 clinical isolates of MRSA, either alone or in combination with antibiotics. The acacetin exhibited a good activity against isolates MRSA with MICs/MBCs ranged between 10-80/20-160 μg/mL, for ampicillin 64-1024/128-2048 μg/mL, and for oxacillin 8-32/16-64 μg/mL. The combination of acacetin plus oxacillin or ampicillin was reduced by ≥4-fold against isolates MRSA tested, evidencing a synergistic effect as defined by a FICI of ≤0.5. Furthermore, a time-kill study evaluating the growth of the tested bacteria was completely attenuated after 2-5 h of treatment with the 1/2 MIC of acacetin, regardless of whether it was administered alone or with oxacillin (1/2 MIC) or ampicillin (1/2 MIC). In conclusion, acacetin exerted synergistic effects when administered with oxacillin or ampicillin and the antibacterial activity and resistant regulation of acacetin against clinical isolates of MRSA might be useful in controlling MRSA infections.