Molecular analysis of genetic mutations among cross-resistant second-line injectable drugs reveals a new resistant mutation in Mycobacterium tuberculosis.
Mutations causing mono and cross-resistance among amikacin, kanamycin and capreomycin of second-line injectable drugs (SLIDs) namely are not well understood. We investigated 124 isolates of Mycobacterium tuberculosis for mutations within rrs, eis, tlyA and efflux pump (Rv1258c and Rv0194) genes involved in resistance towards SLIDs. The distribution of mutations across these genes were significantly different in strains with mono-resistance or cross-resistance. A new mutation G878A was found in rrs gene, among strains with capreomycin mono-resistant, or in strains with cross-resistance of capreomycin, kanamycin and amikacin. This mutation was associated with the Euro-American X3 lineage (P < 0.0001). Mutations in the two efflux genes Rv1258c and Rv0194 were confined to strains with only capreomycin/amikacin/kanamycin cross-resistance. We further investigated the minimum inhibitory concentration of capreomycin on isolates with new G878A mutation ranging from 8 μg/mL to 64 μg/mL. Inclusion of G878A on new molecular assays could increase the sensitivity of capreomycin resistance detection.
South African Medical Research Council, TB Research Platform, Pretoria, South Africa; University of Pretoria, Department of Internal Medicine, Division of Infectious Disease, Pretoria, South Africa. Electronic address: lesibana.malinga@mrc.ac.za.
Lesibana
L
Malinga
South African Medical Research Council, TB Research Platform, Pretoria, South Africa.
Jeannette
J
Brand
South African Medical Research Council, Biostatistics Unit, Pretoria, South Africa.
Steve
S
Olorunju
University of Pretoria, Department of Internal Medicine, Division of Infectious Disease, Pretoria, South Africa.
Anton
A
Stoltz
South African Medical Research Council, TB Research Platform, Pretoria, South Africa.
Martie
M
van der Walt
D000995:Antitubercular Agents / Q000494:pharmacology*; D004252:DNA Mutational Analysis; D005798:Genes, Bacterial; D007267:Injections; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics*; D017354:Point Mutation
D000995:Antitubercular Agents
Cross-resistance; G878A mutation; Second-line injectable drugs; rrs gene