@article {Vaidyap1824, author = {Shashikant Vaidya and Vidyagouri Shinde and Rupendra Jadhav and Shreyasi Mulye and Abhay Chowdhary and Mohan Kulkarni and Geeta Koppikar}, title = {Relationship between rpoB mutations and minimum inhibitory concentrations of rifampicin in multi drug resistant strains of mycobacterium tuberculosis}, volume = {38}, number = {Suppl 55}, elocation-id = {p1824}, year = {2011}, publisher = {European Respiratory Society}, abstract = {Introduction: Rifampicin (RF) resistance serves as a surrogate marker for detection of multi drug resistant (MDR) strains of Mycobacterium tuberculosis (MTB). Among many mutations identified in rpoB gene, the target gene for detection of RF resistance, few were verified by molecular genetic methods.Aim: To detect and characterize mutations in rpoB region of MDR MTB strains by automated DNA sequencing.To study the relationship between in vitro Minimum Inhibitory Concentrations (MIC) for RF and rpoB mutationsMethods: Absolute concentration method was used to determine MIC of RF for 20 MDR MTB strains.DNA sequencing was carried out in an ABI sequencer.Results: We could detect point mutations in the 81 bp section of a {\textquotedblleft}hot spot{\textquotedblright} region of the rpoB gene of all the MDR strains.Mutations were detected in positions 516,526 and 531, with frequencies of 30\%, 40\%, and 55\%, respectively.It was found that mutations in positions 526 and 531 conferred high-level resistance to RF (MIC{\textquoteright}s >= 128μg/ml).Mutations in positions 516 relate to low-level resistance. (MIC{\textquoteright}s <= 64μg/ml).Double point mutations in 2 isolates in positions 526 \& 531 and 1 isolate in position 516 \& 531 relate to high level resistance (MIC{\textquoteright}s >= 128μg/ml), while 2 isolates in position 516 \& 526 relate to low level resistance (MIC{\textquoteright}s <= 64μg/ml).Conclusion: A relationship between susceptibility to RF and alterations in rpoB gene is observed. However, relationship between gene alteration and drug-resistant phenotype is still unclear, further analysis of the relationship between MICs and gene alteration is necessary.}, issn = {0903-1936}, URL = {https://erj.ersjournals.com/content/38/Suppl_55/p1824}, eprint = {https://erj.ersjournals.com/content}, journal = {European Respiratory Journal} }