Abstract

Annaian Shanmugam, Chendur Palpandi and Subramanium Sambasivam

Present study aims to study the geographical profile of rpoB mutations of Mycobacterium tuberculosis clinical isolates and their correlation with the therapeutic outcome. All the isolates were tested for drug susceptibility testing on Lowenstein-Jensen medium and PCR and DNA sequencing for rpoB gene mutations. Fifty two out of 101(52%) isolates were pan susceptible of which 79% were associated with cure. Thirty five isolates (35%) showed a combined resistance to isoniazid and rifampicin, out of which 63% were associated with treatment failure. Majority (94%) of the isolates from cured patients showed wild type of rpoB sequence; where as 77% of patients who failed the treatment were associated with mutations. Twenty eight out of 38(74%), rifampicin resistant isolates showed commonly occurring mutations such as 531, 526 and 516. Multiple silent mutations between the codons 145 - 184 (out side the hot spot region) are being reported for the first time in this study. Information on the geographical profile of rpoB mutations in M. tuberculosis may therefore facilitate for an improved diagnosis of rifampicin resistance, by increasing the efficacy of the gene sequencing based tests.