Abstract:

Objective To analyze the correlation between Amikacin (Am) resistance and rrs gene mutation in multidrug-resistant Mycobacterium tuberculosis (MDR-MTB). Methods A total of 159 MDR-MTB clinical isolates were selected from the reference laboratory of the Fourth Hospital of Inner Mongolia Autonomous Region in year 2005 and 2015. The absolute concentration method was used to detect the drug resistance rate to Am. At the same time, the rrs gene of Am resistant strains was sequenced, and the minimum inhibitory concentration (MIC) in vitro was determined by microplate Alamar Blue assay (MABA). Based on results of test using the absolute concentration method, receiver operating characteristic curve (ROC curve) of MIC value for diagnosis of the drug resistance of Am was made. Results Among the MDR-MTB strains isolated in 2005,18(24.0%,18/75) were resistant to Am, as to those in 2015, the proportion was 27 (32.1%, 27/84). Of the Am resistant MDR-MTB strains, 44(97.8%) had A1401G mutation and 10 (22.2%) had T1384A mutation. Analysis of ROC curve showed that the cut-off value of Am was 1.5 μg/ml, the corresponding sensitivity was 91.1%, and the corresponding specificity was 98.2%. Conclusion A1401G and T1384A mutations in rrs gene of MDR-MTB strains were associated with Am resistance. The MIC value of 1.5 μg/ml could be used to distinguish the sensitivity and resistance of MDR-MTB strains to Am.

Key words: Mycobacterium tuberculosis, Tuberculosis,multidrug-resistant, Amikacin, Microbial sensitivity tests, Genes, Mutation