title: In vitro activity of curcumin in combination with epigallocatechin gallate (EGCG) versus multidrug-resistant Acinetobacter baumannii.
abstract: BACKGROUND
  Acinetobacter baumannii is an opportunistic human pathogen often associated with life-threatening infections in the immunocompromised and the critically ill. Strains are often multidrug-resistant (MDR) and due to the lack of new synthetic antimicrobials in development for treatment, attention is increasingly focused on natural compounds either as stand-alone or adjunctive agents. Curcumin (CCM) is a natural polyphenol found in turmeric and isolated from the plant, Curcuma longa. Curcumin has been found to possess many biological properties, including antibacterial activity. In this study the antimicrobial activity of CCM and synergistic effects with epigallocatechin gallate (EGCG) against multidrug-resistant strains of A. baumannii were investigated and assessed via checkerboard and time-kill assays.
  
  
  RESULTS
  The MIC of CCM was >256 μg/mL against all strains of A. baumannii whilst those for EGCG ranged from 128-1024 μg/mL. In checkerboard studies synergy was observed against 5/9 isolates, with an additive effect noted in the remaining 4. The addition of EGCG reduced the MIC of CCM by 3- to 7-fold, with the greatest interaction resulting in a CCM MIC of 4 μg/mL. Time-kill curves indicated that a CCM-EGCG (1:8 and 1:4) combination was bactericidal with a 4 to 5-log reduction in viable counts after 24 h compared to the most effective polyphenol alone.
  
  
  CONCLUSIONS
  This study demonstrates that despite little antibacterial activity alone, CCM activity is greatly enhanced in the presence of EGCG resulting in antibacterial activity against MDR A. baumannii. The combination may have a potential use in medicine as a topical agent to prevent or treat A. baumannii infections.
authors: Jonathan W
authors: JW
authors: Betts
authors: Antimicrobial Research Group, Centre for Immunology and Infectious Disease, Blizard Institute, Queen Mary University London, 4, Newark Street, Whitechapel, London E1 2AT, UK. d.w.wareham@qmul.ac.uk.
authors: David W
authors: DW
authors: Wareham
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D015169:Colony Count, Microbial; D003474:Curcumin / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004357:Drug Synergism; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D002392:Catechin; C045651:epigallocatechin gallate; D003474:Curcumin