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Thirteen extensively drug-resistant tuberculosis isolates which were highly resistant to a broad spectrum of antituberculosis drugs were identified from 1,926 clinical isolates in China. They had highly diverse mycobacterial interspersed repetitive-unit-variable-number tandem-repeat patterns. Most, but not all, of the drug target genes had mutations contributing to resistance to the corresponding drug.
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Sun et al. (2008) studied this question.
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