Does bilberry inhibit vancomycin intermediate Staphylococcus aureus?

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Does bilberry inhibit vancomycin intermediate Staphylococcus aureus?


Author: Chung, Wing Yee Ruby
Title: Does bilberry inhibit vancomycin intermediate Staphylococcus aureus?
Degree: M.Sc.
Year: 2012
Subject: Bilberry -- Therapeutic use.
Methicillin resistance.
Staphylococcus aureus.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Health Technology and Informatics
Pages: x, 123 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record:
Abstract: Introduction: The rise in methicillin-resistant Staphylococcus aureus (MRSA) and widespread use of vancomycin has led to emergence of MRSA isolates with reduced susceptibility to vancomycin and becoming a threat to humans as there is no standardized therapy for those isolates. Therefore, exploring new therapy against vancomycin-non-susceptible strains is crucial. Some plant products like bilberry have shown some effects against bacteria in previous study. Aim: The purpose of this study was to investigate the synergistic effects of bilberry with vancomycin on vancomycin intermediate S. aureus (VISA) and compare the vancomycin susceptibility of VISA with and without the presence of bilberry. Method: The optimal pH value, the MIC50 and MIC90 (the minimal concentrations to inhibit 50% and 90% of the test isolates respectively) of commercial bilberry extracts and fresh bilberry on test strains were determined by agar dilution method. The Spiral Gradient Endpoint (SGE) method was then used to determine the synergistic effects of commercial bilberry extracts and fresh bilberry with vancomycin on test strains. The brain heart infusion (BHI) agars with corresponding pH and concentration of bilberry were prepared for applying the vancomycin in a radial concentration gradient using a Spiral plater. The minimum inhibitory concentrations (MIC) of bilberry together with vancomycin on test strains were determined. Result: Vancomycin MICs of all test strains were sharply reduced (p<0.05) as concentrations of bilberry increased. 0.6mg/mL and 42mg/mL of commercial bilberry extracts and fresh bilberry juice were the most effective concentration to inhibit the growth of VISA and non-VISA strains with vancomycin respectively. MICs of all VISA strains were successfully reduced to susceptible level. Conclusion: The combination of either commercial bilberry extracts or fresh bilberry juice with vancomycin led to a synergistic effect and inhibited VISA strains by lowering their vancomycin MIC. Further studies are needed to determine the role and effective concentration of bilberry together with vancomycin in the treatment of MRSA and VISA.

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