title: In Vitro Synergy of Biochanin A and Ciprofloxacin against Clinical Isolates of Staphylococcus aureus.
abstract: Many clinical isolates of Staphylococcus aureus (S. aureus) are resistant to numerous antimicrobials, including the fluoroquinolones (FQs). Flavonoids such as biochanin A (BCA) are compounds that are naturally present in fruits, vegetables, and plant-derived beverages. The goal of this investigation was to study the possible synergy between the antimicrobial agents BCA and ciprofloxacin (CPFX) when used in combination; CPFX was chosen as a representative FQ compound. We used S. aureus strain ATCC 25923 and 11 fluoroquinolone (FQ)-resistant methicillin-resistant S. aureus (MRSA) strains. Results from the drug susceptibility testing and checkerboard assays show that the minimum inhibitory concentration (MIC) of BCA ranged from 64 µg/mL to 512 µg/mL. When BCA was combined with CPFX, the fractional inhibitory concentration index (FICI) data showed that there was synergy in all 12 of the S. aureus strains tested. No antagonistic activity was observed in any of the strains tested. The results of time-kill tests and agar diffusion tests confirm that there was synergy between BCA and CPFX against S. aureus strains. These results suggest that BCA can be combined with FQs to produce a powerful antimicrobial agent.
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Guoxing
authors.initials: G
authors.lastname: Liu
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Jun-Chao
authors.initials: JC
authors.lastname: Liang
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Xue-Lin
authors.initials: XL
authors.lastname: Wang
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Zhao-Hui
authors.initials: ZH
authors.lastname: Li
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Food Quality and Safety, College of Quartermaster Technology, Jilin University, Changchun 130062, China.
authors.forename: Na
authors.initials: N
authors.lastname: Guo
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Xiu-Ping
authors.initials: XP
authors.lastname: Wu
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Feng-Ge
authors.initials: FG
authors.lastname: Shen
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Ming-Xun
authors.initials: MX
authors.lastname: Xing
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Li-Hui
authors.initials: LH
authors.lastname: Liu
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China. liumy36@163.com.
authors.forename: Ming-Yuan
authors.initials: MY
authors.lastname: Liu
authors.affiliation: Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun 130062, China. yulu225@yahoo.com.cn.
authors.forename: Lu
authors.initials: L
authors.lastname: Yu
mesh_terms: D002939:Ciprofloxacin / Q000494:pharmacology*; D019833:Genistein / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D013053:Spectrophotometry; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D002939:Ciprofloxacin; D019833:Genistein; C004541:biochanin A