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In vitro and In vivo Activity of Theaflavin–Epicatechin Combinations versus Multidrug-Resistant Acinetobacter baumannii

Betts, Jonathan, Hornsey, Michael, Wareham, David W. and La Ragione, Roberto (2017) In vitro and In vivo Activity of Theaflavin–Epicatechin Combinations versus Multidrug-Resistant Acinetobacter baumannii Infectious Diseases and Therapy, 6 (3). pp. 435-442.

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Introduction: Acinetobacter baumannii is an important human nosocomial pathogen; most clinical isolates are multidrug-resistant (MDR). Infections caused by A. baumannii often lead to high morbidity and mortality, with limited treatment options. Owing to the small number of anti-Gram-negative antibiotics in the development pipeline, researchers are looking to other natural compounds. The aim of this study was to determine the in vitro kill kinetics, in vivo efficacy and toxicity of theaflavin-epicatechin combinations against MDR A. baumannii. Methods: Kill-kinetic assays were performed in Mueller Hinton 2 broth over 24 h. Toxicity of the compound in the insect model, Galleria mellonella was investigated. The effect of theaflavin-epicatechin combinations on mortality and morbidity were assessed in Acinetobacter baumannii infected G. mellonella. Larvae were scored for morbidity (melanisation: scale; 0-4) and mortality over 96 h. Results: Kill-kinetic assays revealed that monotherapy had bacteriostatic activity over 24 h, whereas theaflavin-epicatechin combinations were bactericidal (a >3 log reduction in bacterial numbers at 24 h compared with the starting inoculum). Both polyphenols were non-toxic to G. mellonella at concentrations of up to 1000 mg/kg. In vivo treatment assays showed that the combination significantly increased (t-test; p = <0.05) larval survival at 96 h to 86% (±17 standard deviation percentage points [pp]) compared to monotherapy with theaflavin (52% ±14 pp), epicatechin (44% ±25 pp) or PBS (31% ±13 pp). Morbidity was also lower in larvae treated with the combination, compared to monotherapy. Conclusions: Polyphenol combinations produce effective antibacterial action against A. baumannii and show great potential for the treatment of infections caused by MDR A. baumannii.

Item Type: Article
Divisions : Faculty of Health and Medical Sciences > School of Veterinary Medicine
Authors :
Hornsey, Michael
Wareham, David W.
La Ragione,
Date : 21 June 2017
DOI : 10.1007/s40121-017-0161-2
Copyright Disclaimer : © The Author(s) 2017. This article is an open access publication, distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (, which permits any noncommercial use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Uncontrolled Keywords : Acinetobacter; Galleria mellonella; In vivo; Polyphenols; Multidrug-resistant
Additional Information : Enhanced content To view enhanced content for this article go to CB98F0607627E6CD
Depositing User : Clive Harris
Date Deposited : 12 Jul 2017 08:09
Last Modified : 16 Jan 2019 18:54

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