In Vitro Synergism Testing of Three Antimicrobial Agents against Multidrug-Resistant and Extensively Drug-Resistant Mycobacterium tuberculosis by Checkerboard Method
Received Date: Dec 17, 2014 / Accepted Date: Jan 06, 2015 / Published Date: Jan 15, 2015
Abstract
Objective: In view of the national key project for infectious diseases “the retreatment research of tuberculosis”, we determined the in vitro anti-mycobacterial activity of four drugs in the treatment, pasiniazid (Pa), moxifloxacin (Mfx), Rifabutin (Rfb) and rifapentini (Rft) in combination to multidrug-resistant and extensively drug-resistant Mycobacterium tuberculosis.
Method: Three-dimensional checkerboard in Middlebrook 7H9 broth microdilutions was used to detect the fractional inhibitory concentration index (FICI) of anti-tuberculosis drug combination (MfxPa, MfxPaRfb and MfxPaRft) to twenty clinical isolates of Mycobacterium tuberculosis, including ten multidrug-resistant isolates and ten extensively drug-resistant isolates. The test results were interpreted by calculating the FICI to judge the in vitro synergy, with FICI <0. 5 and FICI <0.75 as the basis of two drugs and three drugs have synergy.
Results: The FICI range of MfxPa combination for multidrug-resistant isolates and ten extensively drug-resistant isolates was 0.28-1, only three isolates <0.5, showed synergistic effect. The FICI range of MfxPaRfb combination for ten isolates of multidrug-resistant isolates was from 0.31 to 1.25, two isolates <0.75, showed synergistic effect and for ten isolates of extensively drug-resistant isolates was from 0.53 to 1.25, five isolates <0.75, showed synergistic effect. The FICI range of MfxPaRft combination for ten isolates of multidrug-resistant isolates was from 0.16 to 0.655, all showed synergistic effect and for ten isolates of extensively drug-resistant isolates was from 0.34 to 1.68, five isolates <0.75, showed synergistic effect.
Conclusion: The synergism of MfxPa combination was poor. When a third agent (Rfb or Rft) was added to the combination, the synergistic effect was better. The MfxPaRft combination showed better synergism than MfxPaRfb combination.
Keywords: Multidrug-resistant M. tuberculosis; Extensively drugresistant M. tuberculosis; In vitro synergy; Fractional inhibitory concentration index; Broth microdilution checkerboard
Citation: Yan L, Zhang L, Yang H, Xiao H (2015) In Vitro Synergism Testing Of Three Antimicrobial Agents against Multidrug-Resistant and Extensively Drug- Resistant Mycobacterium Tuberculosis by Checkerboard Method. J Mol Pharm Org Process Res 2: 123. Doi: 10.4172/2329-9053.1000123
Copyright: ©2015 Yan L, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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