Investigation of the invasion of multidrug and extensively drug-resistant Mycobacterium tuberculosis in Asian countries

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We have collected clinical isolates of Mycobacterium tuberculosis and analyzed the correlation between rifampicin and isoniazid resistance and gene mutations by focusing on Myanmar, Bangladesh and Nepal those where the survey of multi and extensively drug-resistant tuberculosis is not sufficient. In Myanmar, mutation rate for ropB encoding region of rifampicin resistant M. tuberculosis and that in katG encoding and inhA regulatory region of isoniazid resistant M. tuberculosis were 71.3 and 72.5%, respectively. On the contrary, higher correlations were observed in other two countries. Those for rifampicin and isoniazid resistant M. tuberculosis were 95.0 and 94.5 %, respectively, in Bangladesh and 97.2 and 93.8 %, respectively, in Nepal. In addition, seven extensively drug resistant M. tuberculosis were found from 218 multi drug-resistant strains, respectively, in Bangladesh. Thirteen extensively drug.resistant tuberculosis were found from 109 multi drug-resistant strains, respectively, in Nepal. All of these isolates carried mutations in rrs and gyrA or gyrB for kanamycin and fluoroquinolone resistance, respectively. As correlations between drug resistance and gene mutations were different between countries, the elucidation of drug resistance associating genes before introducing gene based drug susceptibility tests seemed to be important.