Antibacterial activity of Eleutherine bulbosa against multidrug-resistant bacteria

Background: Recent interest in plant-based medicine is justified, as synthetic antioxidants and antibiotics suffer from several drawbacks. Plant extracts have been shown to possess health promoting properties, and they exert no selective physiological pressure on the pathogens that can result in development of drug resistance. The aim of this study was to investigate the antibacterial activity of Eleutherine bulbosa plant extracts against a series of multidrug-resistant (MDR) bacteria by calculating zones of inhibition, minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs) and time-kill kinetics. Methods: Dried bulb powder of E. bulbosa was extracted with five solvents (ethyl acetate, chloroform, butanol, ethanol and water) to select the best extractant for subsequent isolation of bioactive compounds to use against a battery of MDR bacteria. Results: Butanol was found to be the best extractant with an MIC ranging from 46 mg/mL to 187 mg/mL. Butanol and aqueous extracts showed higher zones of inhibition in comparison with standard antibiotics gentamicin and ciprofloxacin. Thin layer chromatography (TLC)-bioautography was carried out with the butanol extract against Staphylococcus aureus and Shigella boydii. A synergistic effect was established against S. boydii by combining the chloroform extract with gentamicin. Conclusion: The bulb extracts of E. bulbosa exhibited significant antibacterial activity. Further study is necessary to characterize the antibacterial compounds of this plant for use in clinical applications. Copyright (C) 2015, Taiwan Society of Emergency Medicine. Published by Elsevier Taiwan LLC. All rights reserved.