title: Synergistic effects of the combination of 20-hydroxyecdysone with ampicillin and gentamicin against methicillin-resistant Staphylococcus aureus.
abstract: The emergence of methicillin-resistant of Staphylococcus aureus (MRSA) has led to an urgent need for the discovery and development of new antibacterial agents. As part of an ongoing investigation into the antibacterial properties of the natural products, 20-Hydroxyecdysone (20E), isolated from the roots of Achyranthes japonica Nakai, was found to be active methicillin-resistant Staphylococcus aureus (MRSA), either alone or in combination with ampicillin (AM) or gentamicin (GM), vis checkerboard assay. This study investigated the antibacterial activity of 20E, which exhibited poor antibacterial activity (MIC=250-500 microg/mL) against all the bacterial strains tested. The combined activity of ampicillin (AM), gentamicin (GE) plus 20E against MRSA resulted in fractional inhibitory concentrations (FICs) ranging from 4.00 to 0.031 microg/mL, respectively. Meanwhile, the FIC index ranged from 0.16-4.50, indicating a marked synergistic relationship between AM, GE and 20E against MRSA with enterotoxin gene. Time-kill assays also showed a decrease remarkably between the combination and the more active compound. Therefore, this study demonstrated that AM, GE, and 20E can act synergistically in inhibiting MRSA in vitro.
authors.affiliation: Vestibulocochlear Research Center & Department of Microbiology, School of Medicine, Wonkwang University School of Medicine, Iksan 570-749, South Korea.
authors.forename: Eun Sook
authors.initials: ES
authors.lastname: Kim
authors.forename: Seung-Il
authors.initials: SI
authors.lastname: Jeong
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Channy
authors.initials: C
authors.lastname: Park
authors.forename: Shin-Moo
authors.initials: SM
authors.lastname: Kim
authors.forename: Jin-Kyung
authors.initials: JK
authors.lastname: Kim
authors.forename: Kang-Min
authors.initials: KM
authors.lastname: Lee
authors.forename: Sang-Heon
authors.initials: SH
authors.lastname: Lee
authors.forename: Hongseob
authors.initials: H
authors.lastname: So
authors.forename: Rakil
authors.initials: R
authors.lastname: Park
mesh_terms: D029044:Achyranthes / Q000737:chemistry; D000667:Ampicillin / Q000494:pharmacology* / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004441:Ecdysterone / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D005839:Gentamicins / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D018517:Plant Roots / Q000737:chemistry; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D010936:Plant Extracts; D004441:Ecdysterone; D000667:Ampicillin