Correlating rrs and eis promoter mutations in clinical isolates of Mycobacterium tuberculosis with phenotypic susceptibility levels to the second-line injectables.

The in vitro drug-susceptibility testing of Mycobacterium tuberculosis reports isolates as resistant or susceptible on the basis of single critical concentrations. It is evident that drug resistance in M. tuberculosis is quite heterogeneous, and involves low level, moderate level, and high level of drug-resistant phenotypes. Thus, the aim of our study was to correlate rrs (X52917) and eis (AF144099) promoter mutations, found in M. tuberculosis isolates, with corresponding minimum inhibitory concentrations of amikacin, kanamycin, and capreomycin. Ninety M. tuberculosis clinical isolates were analyzed in this study. The minimum inhibitory concentrations were determined by MGIT 960 for 59 isolates with resistance-associated mutations in the rrs and eis promoter gene regions, and 31 isolates with wild-type sequences, as determined by the GenoType MTBDRsl (version 1) assay. The rrs A1401G mutation was identified in 48 isolates resistant to the second-line injectables. The eis promoter mutations C-14T (n=3), G-10C (n=3), G-10A (n=3), and C-12T (n=2) were found within 11 isolates with various resistance profiles to the second-line injectables. Thirty-one isolates had wild-type sequences for the rrs and eis promoter gene regions of interest, one of which was amikacin, kanamycin, and capreomycin resistant. The isolates with the rrs A1401G mutation had amikacin, kanamycin, and capreomycin minimum inhibitory concentrations of >40mg/L, >20mg/L, and 5-15mg/L, respectively. The isolates with eis promoter mutations had amikacin, kanamycin, and capreomycin minimum inhibitory concentrations of 0.25-1.0mg/L, 0.625-10mg/L, and 0.625-2.5mg/L, respectively. This study provides a preliminary basis for the prediction of phenotypic-resistance levels to the second-line injectables based upon the presence of genetic mutations associated with amikacin, kanamycin, and capreomycin resistance. The results suggest that isolates with eis promoter mutations have consistently lower resistance levels to amikacin, kanamycin, and capreomycin than isolates with the rrs A1401G mutation.

Kambli P ，Ajbani K ，Nikam C ，Sadani M ，Shetty A ，Udwadia Z ，Georghiou SB ，Rodwell TC ，Catanzaro A ，Rodrigues C ... -  《-》

Mycobacterium tuberculosis rrs A1401G mutation correlates with high-level resistance to kanamycin, amikacin, and capreomycin in clinical isolates from mainland China.

Mutations correlating phenotypic resistance level with the injectable second-line anti-tuberculosis drugs (SLDs) including kanamycin (KAN), amikacin (AMK), and capreomycin (CAP) remain elusive. A collection of 114 Mycobacterium tuberculosis clinical isolates from mainland China was analyzed. The minimum inhibitory concentration (MIC) of each strain was determined and the sequences of rrs, tlyA, promoter of eis as well as 5' untranslated region (UTR) of whiB7 were amplified and sequenced. No mutation in tlyA, promoter of eis and 5' UTR of whiB7, was found to be associated with resistance among these samples. Sequencing data of 1400 rrs region demonstrated the A1401G mutation in rrs was prevalent, which presented in 84% of the KAN resistant isolates while only in about 50% of the AMK or CAP resistant isolates. Furthermore, most of the resistant isolates with A1401G mutation showed high-level resistance to these injectable SLDs. In conclusion, our results suggest the rrs A1401G mutation was related to high-level resistance to KAN, AMK, and CAP in M. tuberculosis isolates from mainland China.

Du Q ，Dai G ，Long Q ，Yu X ，Dong L ，Huang H ，Xie J ... -  《-》

Comparison of clinical isolates and in vitro selected mutants reveals that tlyA is not a sensitive genetic marker for capreomycin resistance in Mycobacterium tuberculosis.

Engström A ，Perskvist N ，Werngren J ，Hoffner SE ，Juréen P ... -  《-》

High level of cross-resistance between kanamycin, amikacin, and capreomycin among Mycobacterium tuberculosis isolates from Georgia and a close relation with mutations in the rrs gene.

Jugheli L ，Bzekalava N ，de Rijk P ，Fissette K ，Portaels F ，Rigouts L ... -  《-》

Evaluation of genetic mutations associated with Mycobacterium tuberculosis resistance to amikacin, kanamycin and capreomycin: a systematic review.

Georghiou SB ，Magana M ，Garfein RS ，Catanzaro DG ，Catanzaro A ，Rodwell TC ... -  《PLoS One》