title: Antibacterial and synergy of a flavanonol rhamnoside with antibiotics against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA).
abstract: The in vitro antibacterial activity of taxifolin-7-O-α-L-rhamnopyranoside (TR) and its synergy with four conventional antibiotics (ampicillin (AMP), levofloxacin (LEV), ceftazidime (CAZ) and azithromycin (AZM)) against ten clinical isolates of methicillin-resistant staphylococcus aureus (MRSA) were evaluated, respectively. Individual MICs and MBCs were determined by microdilution methods following the CLSI guidelines. Anti-MRSA synergy effects were measured using the chequerboard and time-kill curve tests. MICs/MBCs (μg/ml) ranges were 32-64/64-128 for TR alone against all 10 MRSA isolates. Chequerboard method showed that significant synergies were observed for the TR/CAZ and TR/LEV combinations with FICI ranged 0.187-0.375 and 0.25-0.5, respectively. Some synergy and additivity effects were also observed for TR/AMP and TR/AZM combinations. In the time-kill dynamic confirmation test, synergy results kept by the TR/CAZ combination (2.186 log₁₀ cfu/ml increase in killing), but the TR/LEV combination changed to additivity (1.839 log₁₀ cfu/ml increase in killing). These results demonstrated that TR enhanced the efficacy of CAZ and LEV in vitro, which had potential for combinatory therapy of patients infected with MRSA.
authors.affiliation: Research Center for Natural Medicines, Kunming General Hospital, PLA, 212 Da Guan Road, 650032 Kunming, China.
authors.forename: J
authors.initials: J
authors.lastname: An
authors.forename: G Y
authors.initials: GY
authors.lastname: Zuo
authors.forename: X Y
authors.initials: XY
authors.lastname: Hao
authors.forename: G C
authors.initials: GC
authors.lastname: Wang
authors.forename: Z S
authors.initials: ZS
authors.lastname: Li
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017963:Azithromycin / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology; D004357:Drug Synergism; D044948:Flavonols / Q000494:pharmacology*; D006027:Glycosides / Q000494:pharmacology*; D006801:Humans; D020902:Hypericum / Q000737:chemistry*; D064704:Levofloxacin; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D015242:Ofloxacin / Q000494:pharmacology; D011794:Quercetin / Q000031:analogs & derivatives* / Q000494:pharmacology; D013183:Sputum / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D044948:Flavonols; D006027:Glycosides; C568786:taxifolin-7-O-alpha-L-rhamnopyranoside; D064704:Levofloxacin; D000667:Ampicillin; D017963:Azithromycin; D011794:Quercetin; D002442:Ceftazidime; D015242:Ofloxacin