title: In vitro synergistic antibacterial activities of helvolic acid on multi-drug resistant Staphylococcus aureus.
abstract: An agar plate method was established to screen synergistic antibacterial agents other than beta-lactamase inhibitors. By using this method, a strain Aspergillus sp136 was selected for further studies. From the metabolites of this strain, a synergistic antibacterial compound was isolated by bioautographic TLC assay-guided fractionation and identified as helvolic acid. The synergistic effect of helvolic acid to penicillin was about 3 times that of clavulanic acid to penicillin in agar diffusion assay on Bacillus cereus. In checkerboard studies, helvolic acid exhibited synergistic effects with erythromycin on all tested multi-drug resistant Staphylococcus aureus and with penicillin and tetracycline on some multi-drug resistant S. aureus. A pattern of enhanced killing was also found in time-kill studies on multi-drug resistant S. aureus.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, People's Republic of China.
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.forename: Bogang
authors.initials: B
authors.lastname: Li
authors.forename: Jiafa
authors.initials: J
authors.lastname: Guan
authors.forename: Guolin
authors.initials: G
authors.lastname: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001409:Bacillus cereus / Q000187:drug effects; D019818:Clavulanic Acid / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D005672:Fusidic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010406:Penicillins / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins; D019818:Clavulanic Acid; D005672:Fusidic Acid; C011267:helvolic acid