Rapid genotypic detection of rpoB and katG gene mutations in Mycobacterium tuberculosis clinical isolates from Northern India as determined by MAS-PCR.

BACKGROUND

There is a growing need to develop rapid laboratory research methods to counter the menace of drug resistant tuberculosis (MDR-TB) cases worldwide especially in developing countries. The present study was undertaken to investigate the type and frequency of rpoB and katG mutations in rifampicin (RIF) and isoniazid (INH) resistant strains respectively of Mycobacterium tuberculosis (MTB) circulating in Northern India and to explore the utility of multiplex-allele-specific (MAS)-PCR assay for detection of drug-resistant MTB isolates in low resource set up.

METHODS

Phenotypic and genotypic drug susceptibility testing (DST) was performed on 354 MTB isolates.

RESULTS

Mutation in rpoB gene was found most frequently at codons 531, 526 and 516 (59.83%, 45.29% and 22.22%, respectively). Further, combinations of 2-3 point mutations were also observed in 19.66% of RIF-resistant MTB strains. The frequency of mutations in katG gene was found at codon 315 among 82.95% of the INH-resistant MTB isolates. MAS-PCR detected rpoB and katG mutations in phenotypically resistant isolates with sensitivities of 93% and 83% respectively.

CONCLUSION

MAS-PCR assays can be used for rapid detection of drug-resistant TB strains in routine diagnostic practice, enabling early administration of appropriate treatment regimens to the affected patients.