Genetic evaluation of relationship between mutations in rpoB and resistance of Mycobacterium tuberculosis to rifampinReportar como inadecuado

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BMC Microbiology

, 9:10

First Online: 15 January 2009Received: 17 October 2008Accepted: 15 January 2009


BackgroundRifampin is a first line antituberculosis drug active against bacilli in logarithmic and stationary phase, which interferes with RNA synthesis by binding to bacterial RNA polymerase. Tubercle bacilli achieve resistance to rifampin by accumulation of mutations in a short-81 bp region of the rpoB gene. Among many mutations identified in the rpo B gene, few were verified by molecular genetic methods as responsible for resistance to rifampin RMP.

ResultsIn this study eight different mutations identified in an 81 bp section of a -hot spot- region of the rpo B gene of RMP resistant Mycobacterium tuberculosis clinical strains were evaluated in respect to drug resistance. It was found that: mutations in positions 526 H-D, 516 D-V and 531 S-L result in high level resistance to rifampin; mutations in positions 516 D-Y, 515 M-I, 510 Q-H or a double mutation in codons 512 S-I and 516 D-G relate to low level of resistance. Gene rpo B carrying mutations in codon 513 Q-L introduced into an M. tuberculosis laboratory strain did not cause resistance to rifampin, however the same gene introduced into two different clinical strains did, with the level of resistance depending on the host strain.

ConclusionMutations in an 81 bp -hot spot- region of the rpoB of M. tuberculosis lead to different levels of resistance to rifampin. Some mutations in this -hot spot- region of rpoB require a specific genetic background for the host strain to develop resistance to rifampin. Therefore, the identification of such mutations in a clinical M. tuberculosis strain is not enough to classify the given strain as resistant to rifampin.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2180-9-10 contains supplementary material, which is available to authorized users.

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Autor: Anna Zaczek - Anna Brzostek - Ewa Augustynowicz-Kopec - Zofia Zwolska - Jaroslaw Dziadek


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