Abstract: Objective To analyze drug susceptibility profiles of multi-drug resistant (MDR) M. tuberculosis isolated from China, and provide the scientific evidence for MDR-tuberculosis (MDR-TB) control and prevention. Methods One hundred and twenty-six MDR isolates were selected from the first drug resistant survey in China between April 2008 and July 2008. The conventional drug susceptibility testing was used to detect the drug-resistant profiles against 2 first-line (streptomycin and ethambuol) and 7 second-line anti-tuberculosis drugs (ofloxacin, kanamycin, capreomycin, ethionamide, protionamide，cycloserine and 4-Amino-2-hydroxybenzoicacid). The drug-resistant proportion and cross resistance were analyzed. Results For first-line drugs, the drug-resistant proportions against streptomycin and ethambuol were 73.0% (92/126) and 58.7% (74/126), respectively. For second-line drugs, the percentages of the resistance to ofloxacin and ethionamide were the highest, accounting for 25.4% (32/126) and 23.0% (29/126), respectively. Then, 17.5% (22/126) and 13.5% (17/126) of MDR strains were resistant to kanamycin and cycloserine, respectively. In addition, the drug-resistant rates of capreomycin, protionamide and 4-Amino-2-hydroxybenzoicacid were all 3.2% (4/126). The drug-resistant proportions of kanamycin (χ²=20.025，P<0.01) and cysloserine (χ²=6.558，P=0.017) in new case group were significantly higher than that in re-treated case group. In addition, there were the cross-resistances between kanamycin and capreomycin, or ethionamide and protionamide. Three of four capreomycin-resistant isolates were resistant to kanamycin, and all four protionamide-resistant strains were resistant to ethionamide meanwhile. Conclusion The high prevalence of M. tuberculosis strains with the resistance to second-line anti-tuberculosis drugs, especially to ofloxacin and ethionamide in MDR-TB patients was the major challenge on the prevention and control of TB and MDR-TB in China.

Key words: Mycobacterium tuberculosis, Drug resistance, multiple, bacterial, Antibiotics, antitubercular, Microbial sensitivity tests