Phenotypic and Genotypic Characterization of Multi-Drug Resistant Mycobacterium tuberculosis

Abstract

This study characterized multi-drug resistant M. tuberculosis phenotypically by LJ-proportion method and genotypically by Geno Type MTBDR plus LPA. Out of the forty M. tuberculosis isolates tested, two (5.0%) were found to be multi-drug resistant by LJ proportion method and one (2.5%) was MDR by LPA. None was found to be mono-resistant to any of the drugs by LJ however, one isolate was mono resistant to RIF and one was mono resistant to INH by LPA. Comparison of Geno Type MTBDRplus LPA and phenotypic LJ-proportion methods showed that one isolate was mono resistant to RIF and one was mono resistant to INH by LPA, one and two MDR-TB isolates respectively were characterized by genotypic and phenotypic methods. The remaining isolates were found to be pan susceptible by both methods. One isolate was characterized as MDR with bands at rpoβ MUT2A region and ihnA MUT2 corresponding to H526Y and A16G mutations respectively. Rifampicin mono resistance with band at rpoβ MUT3 corresponding to S531L was found in one isolate. Also, isoniazid mono resistance was observed in one isolate with ihnA MUT2 band corresponding to A16G mutation. This study has shown an overall high prevalence of MDR-TB in the study area which needs to be urgently addressed. Laboratory facilities for rapid drug resistance detection are needed across the country for early and accurate diagnosis of TB and drug resistant cases. This remains an important step in managing TB drug resistance in Nigeria.