The Journal of Toxicological Sciences
Online ISSN : 1880-3989
Print ISSN : 0388-1350
Synergistic effect of tetrandrine and ethidium bromide against methicillin-resistant Staphylococcus aureus (MRSA)
Young-Seob LeeSin-Hee HanSu-Hwan LeeYoung-Guk KimChung-Berm ParkOk-Hwa KangJoon-Ho KeumSung-Bae KimSu-Hyun MunDong-Won ShinDong-Yeul Kwon
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2011 Volume 36 Issue 5 Pages 645-651


Methicillin-resistant Staphylococcus aureus (MRSA) along with other resistant bacteria have become a significant social and clinical problem. Therefore, there is an urgent need to develop bioactive compounds from natural products as alternatives to the very few antibiotics that remain effective. Recently, the efflux mechanism has been identified as the main contributor to antibiotic resistance in bacteria. This study therefore aimed to evaluate tetrandrine (TET), an efflux pump inhibitor (EPI), as a potential antibiotic against MRSA. We investigated the antimicrobial activity of TET against 17 MRSA strains, of which 3 selected strains were studied in further detail using a time-kill assay. When these bacterial strains (1 × 106 colony-forming units (cfu)/ml) were incubated with TET in a time-kill assay, log-scale bactericidal activity was observed, which lasted for 24 hr. In addition, TET exhibits a synergistic effect when combined with the multi-drug resistance (MDR)-efflux pump substrate ethidium bromide (EtBr). Structure-function studies of the antibiotic activity of TET in combination with EtBr may lead to the discovery of more effective efflux pump inhibitors.

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© 2011 The Japanese Society of Toxicology
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