Usharani Brammacharry, Muthuraj Muthaiah
American Journal of Microbiological Research. 2014, 2(3), 80-85DOI:
Abstract: The worldwide emergence and spread of drug - resistant strains of Mycobacterium tuberculosis has adverse effects on tuberculosis (TB) control programs. The goal of this paper is to describe the advances made in the understanding of the molecular basis of M. tuberculosis resistance to streptomycin and to discuss the potential of molecular methods in early diagnosis of streptomycin resistant TB.Molecular methods such as DNA sequencing, polymerase chain reaction have been used to identify/detect mutations in rpsL gene-encoding proteins.Of the 77 SM resistant isolates, 22 (28.6%) exhibited mutation at codon 43 Lys→Arg, 11 (14.3%) isolates exhibited mutation at codon 83 Arg→Gln, 9(%) isolates exhibited mutation at codon 95 Tyr→His,whereas remaining 23 (40.8%) SM resistant isolates showed no mutation in rpsL gene. Among the 77 SM resistant isolates, 31(40.2%) were SM mono resistant and 46(59.8%) strains were poly resistant. All the 23 SM susceptible isolates as well as reference strain M.tuberculosis H37Rv exhibited wild type sequences of rpsL gene. Molecular methods to detect the most frequent mutations in the gene encoding functions that are targets for streptomycin drug have provided encouraging results for early diagnosis of resistance nature.