Study On The Combined Effect Of Core Drugs On MDR-Mtb And XDR-Mtb In Vitro

Objective In view of the national subject of infectious diseases " the retreatment research of tuberculosis", we detect the synergistic effect in vitro of four drugs in the treatment-pasiniazid (Pa), moxifloxacin (Mfx), Rifabutin (Rfb) and rifapentini (Rft)to multidrug-resistant and extensively drug-resistant mycobacterium tuberculosis.Method Detect the MIC value of four drugs (moxifloxacin(Mfx), pasiniazid(Pa), rifabutin(Rfb), rifapentini(Rft)) for 40 strains of known susceptibility results Mtb clinical isolates and standard strain H37Rv, then compare the drug resistance of four drugs. Checkerboard method were used to detect the fractional inhibitory concentration index of antituberculosis drug combination schemes (MfxPa, MfxPaRfb and MfxPaRft) to 40 strains of clinical drug resistance Mtb (20 strains of multidrug-resistant Mtb and 20 extensively drug-resistant strains of Mtb) and standard strain H37Rv, by calculating the fractional inhibitory concentration index of joint action in vitro to judge the 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 scheme for MDR and XDR-Mtb is 0.125-1, only five strains of FICI≤0.5, show synergistic effect. The FICI of MfxPaRfb scheme with 20 srains of multidrug-resistant Mtb ranges from 0.31 to 1.26,ten strains of FICI≤0.75,which have synergistic effect. The FICI of MfxPaRfb scheme with 20 srains of extensively drug-resistant Mtb ranges from 0.215to 1.25, eleven strains of FICI≤0.75, which have synergistic effect. The FICI of MfxPaRft scheme with 20 srains of multidrug-resistant Mtb ranges from 0.15to 0.78, nineteen strains of FTC≤0.75, which have synergistic ettect. The FICT of MfxPaRft scheme with 20 srains of extensively drug-resistant Mtb ranges from 0.2to 1.28, sixteen strains of FICI≤0.75, which have synergistic effect.Conclusion Mfx, Pa, Rfb have good bacteriostatic action to drug-resistant Mtb, and are recommended for clinical treatment of MDR-tb. The synergy effect of MfxPa scheme is poor, it shows better synergy when futher joint Rfb or Rft, but the synergistic effect of MfxPaRfb combination scheme is poor than MfxPaRft combination scheme.