Planta Med 2008; 74(8): 840-846
DOI: 10.1055/s-2008-1074559
Pharmacology
Original Paper
© Georg Thieme Verlag KG Stuttgart · New York

The Effects of Antibiotics Combined with Natural Polyphenols against Clinical Methicillin-Resistant Staphylococcus aureus (MRSA)

Rong-Dih Lin1 , 2 , Yi-Ping Chin3 , Wen-Chi Hou4 , Mei-Hsien Lee4
  • 1Department of Internal Medicine, Ho-Ping Branch, Taipei City Hospital, Taipei, Taiwan
  • 2School of Bio-resources Technology, College of Pharmacy, Taipei Medical University, Taipei, Taiwan
  • 3Department of Microbiology and Immunology, Taipei Medical University, Taipei, Taiwan
  • 4Graduate Institute of Pharmacognosy, College of Pharmacy, Taipei Medical University, Taipei, Taiwan
Further Information

Publication History

Received: August 13, 2007 Revised: May 2, 2008

Accepted: May 5, 2008

Publication Date:
10 June 2008 (online)

Zoom Image

Abstract

Novel therapies are needed to address the public health problem posed by methicillin-resistant Staphylococcus aureus (MRSA). In this study, we determined the effects of combinations of antibiotics and plant polyphenols against 20 clinical isolates of MRSA. The in vitro activities of 10 antibiotics and 15 natural polyphenols against the isolates were evaluated by determining minimum inhibitory concentrations (MICs). All isolates were susceptible to vancomycin and resistant to rifampicin, while susceptibilities to ciprofloxacin varied. Among the 15 natural polyphenols, kaempferol (3,4′,5,7-tetrahydroxyflavone) and quercetin (3,3′,4′,5,7-pentahydroxyflavone) showed the lowest MICs. In checkerboard assays, combinations of rifampicin and either kaempferol or quercetin acted synergistically or partially synergistically against the clinical MRSA isolates. Rifampicin combined with kaempferol or quercetin exhibited good β-lactamase inhibitory effects (57.8 % and 75.8 %, respectively) against a representative isolate according to nitrocefin analysis. The study results and ready availability and low toxicity of plant polyphenols warrant further investigations on the therapeutic potential of combination therapies for MRSA infections.

Abbreviations

FIC:fractional inhibitory concentration

MIC:minimum inhibitory concentration

MRSA:methicillin-resistant Staphylococcus aureus