Abstract:

In order to compare and analyze the drug-susceptibility of multidrug-resistant Mycobacterium tuberculosis (MDR-MTB) to linezolid (Lzd) and tedizolid (Tzd), 40 isolates, which were isolated and identified as MDR-MTB by drug susceptibility test in the central laboratory from Jan. 2018 to Nov. 2018, were selected from Chongqing Public Health Medical Center by direct selection method. Minimum inhibitory concentrations (MIC) of Lzd and Tzd against these isolates were determined by microplate method and the relative data were analyzed. The results showed that the MIC (M(Q₁,Q₃)) of Lzd against to MDR-MTB isolates was 0.500 (0.500, 1.000) mg/L, of which 87.5% (35/40) of the strains had MIC of 0.500-1.000 mg/L. And the MIC (M(Q₁,Q₃)) of Tzd against to MDR-MTB isolates was 0.250 (0.250, 0.250) mg/L, of which 87.5% (35/40) of the strains were in the range of 0.125-0.250 mg/L. The MIC₅₀ and MIC₉₀ of Lzd against to MDR-MTB isolates were 0.500 and 1.000 mg/L, respectively, while those of Tzd against to MDR-MTB isolates were both 0.250 mg/L. The MIC of Tzd was obviously lower than that of Lzd (Z=-5.51, P<0.001). According to the results of the proportional susceptibility test, 40 MDR-MTB clinical isolates were identified as 13 strains of MDR-MTB, 20 strains of pre-extensive drug-resistant Mycobacterium tuberculosis (pre-XDR-MTB) and 7 strains of XDR-MTB. The MICs (M(Q₁,Q₃)) of Lzd against to MDR-MTB, pre-XDR-MTB and XDR-MTB isolates were 0.500 (0.500, 1.000) mg/L; while those of Tzd were 0.250 (0.250, 0.250) mg/L, without significant difference between the MICs of Lzd or Tzd among MDR-MTB, pre-XDR-MTB and XDR-MTB (Lzd: H=0.84, P=0.659; Tzd: H=0.59, P=0.746). In conclusion, both Lzd and Tzd have good bactericidal effects on MDR-MTB strains, and the anti-tuberculosis effect of Tzd was better than that of Lzd.

Key words: Mycobacterium tuberculosis, Drug resistance, multiple, Oxazolidinones, Microbial sensitivity tests