Author(s):
Abreu, Ana Cristina ; Serra, Sofia Cravino ; Borges, Anabela ; Saavedra, Maria J. ; Mcbain, Andrew J. ; Salgado, A. J. ; Simões, Manuel
Date: 2015
Persistent ID: http://hdl.handle.net/1822/51445
Origin: RepositóriUM - Universidade do Minho
Project/scholarship:
info:eu-repo/grantAgreement/FCT/5876-PPCDTI/105085/PT
;
info:eu-repo/grantAgreement/FCT/5876-PPCDTI/125925/PT
;
info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBD%2F84393%2F2012/PT;
info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBD%2F63398%2F2009/PT;
Subject(s): Science & Technology
Description
The use of resistance-modifying agents is a potential strategy that is used to prolong the effective life of antibiotics in the face of increasing antibiotic resistance. Since certain flavonoids are potent bacterial efflux pump inhibitors, we assessed morin, rutin, quercetin, hesperidin, and (+)-catechin for their combined activity with the antibiotics ciprofloxacin, tetracycline, erythromycin, oxacillin, and ampicillin against drug-resistant strains of Staphylococcus aureus, including methicillin-resistant S. aureus. Four established methods were used to determine the combined efficacy of each combination: microdilution checkerboard assays, time-kill determinations, the Etest, and dual disc-diffusion methods. The cytotoxicity of the flavonoids was additionally evaluated in a mouse fibroblast cell line. Quercetin and its isomer morin decreased by 3- to 16-fold the minimal inhibitory concentration of ciprofloxacin, tetracycline, and erythromycin against some S. aureus strains. Rutin, hesperidin, and (+)-catechin did not promote any potentiation of antibiotics. Despite the potential cytotoxicity of these phytochemicals at a high concentration (fibroblast IC50 of 41.8 and 67.5mg/L, respectively), quercetin is commonly used as a supplement for several therapeutic purposes. All the methods, with exception of the time-kill assay, presented a high degree of congruence without any apparent strain specificity.
This work was supported by Operational Program for Competitiveness Factors—COMPETE, FCT/MEC (PIDDAC), and FEDER through Projects Bioresist—PTDC/EBB-EBI/ 105085/2008; Phytodisinfectants—PTDC/DTP-SAP/1078/ 2012 (COMPETE: FCOMP-01-0124-FEDER-028765) and the PhD grants awarded to Ana Abreu (SFRH/BD/84393/ 2012) and Anabela Borges (SFRH/BD/63398/2009). The authors are very grateful to Professor Simon Gibbons (De- partment of Pharmaceutical and Biological Chemistry, The School of Pharmacy, UCL School of Pharmacy, London) for providing the bacterial strains.
info:eu-repo/semantics/publishedVersion
