Studies on molecular mechanism of ethambutol resistance in Mycobacterium tuberculosis clinical isolates
Wu Xue-qiong 1,Liang Jian-qin 2,Li Hong-min 1,Zhang Jun-xian 1, You Kun 1,Jin Guan-pu 1,Liu Jia-wen 3andYan Guo-rui 4 (1 Tuberculosis Research Laboratory, The 309th Hospital of PLA,Beijing 100091; 2 The Chest Hospital of Hebei Province,Shijiazh
ObjectiveTo study the molecular mechanisms of ethambutol resistance in Mycobacterium tuberculosis, and develope a new method for detecting drug resistance. Method107 clinical isolates were identified with their microbacterial species, and then analyzed their embB genes with PCR-SSCP, PCR-RFLP and PCR-Direct Sequencing. ResultMycobacterium tuberculosis strain H 37R V was used as a control. 107 clinical isolates all had the same 16S rDNA SSCP profiles as M.tuberculosis. 38 drug-sensitive isolates had normal embB SSCP and RFLP profiles. Of 69 ethambutol-resistant isolates, 25(36.2%) displayed abnormal embB SSCP profiles; 8 isolates had abnormal RFLP profiles. All of embB mutations situated at codon 306 (1 of these had another mutation at codon 274), which EMB MICs were more than 20μg/ml. 8 isolates had ATG to ATA or ATT mutations at codon 306; 17 isolates had ATG to GTG or CTG mutations at codon 306, which EMB MICs were more than 30μg/ml. ConclusionEthambutol resistance in some M.tuberculosis isolates were due to mutations on embB genes. PCR-SSCP method might become a simple and rapid diagnostic test for genotypes of M.tuberculosis ethambutol-resistance.
【CateGory Index】： R378