The Glutoxim influence on minimum inhibitory concentration of isoniazid-resistant strains of Mycobacterium tuberculosis

<b>Background:</b> The spreading of Mycobacterium tuberculosis (Mtb) strains with resistance to isoniazid (I) is a serious challenge. The study of drugs which reduce the minimum inhibitory concentration (MIC) of I for I-resistant strains it seems promising. <b>Aim:</b> To study the ability of G to potentiate the antimicrobial action of I on Mtb I-resistant strains. <b>Methods:</b> 52 Mtb strains were obtained from sputum of pulmonary tuberculosis patients with established mono-poly-isoniazid-resistance (BACTEC MGIT 960, BD). The effect of the joint action of G and I were studied using the method of “chessboard” ("checkers") (Orhan G.et al, 2005), in the Middlebrook 7H9 medium with OADC growth additive (BD, USA). The growth of Mtb in the planets was visualized by Resazurin (Sigma) and recorded on a tablet fluorescent spectrophotometer “FLUOstar OPTIMA” (λ_excit – 530 nm, λ_emis - 590 nm). <b>Results:</b> In none of the experimental series G did affect the growth of Mtb. 52 strains were I-resistant (MIC &gt; 0.08 µg/ml), 12 of them had high level of I resistance (MIC &gt; 10.0 µg/ml). G in concentrations from 25.0 µg/ml to 1.6 µg/ml potentiated the I action in 100% and MIC were fined reduced in 2 times. Potentiating activity of G is manifested in the concentration from 50.0 µg/ml at 29 strains. Correlation between the range of working concentrations G and MIC of I were not identified. <b>Conclusions:</b> G reduced the MIC of isoniazid at low and high level of I-resistant strains. Dose-dependent effect G was detected: the most effective concentration was 1.6 µg/ml in which the G reduced MIC of I in 2 times. Overall, potential activity of G appears at concentrations below the level of 50 µg/ml.