eis Promoter C14G and C15G Mutations Do Not Confer Kanamycin Resistance in Mycobacterium tuberculosis.

We studied the significance of particular eis mutations on Mycobacterium tuberculosis drug resistance using a specialized transduction strategy. Recombinant strains harboring eis promoter mutations C14T, C12T, and G10A exhibited kanamycin resistance with MICs of 40, 10, and 20 µg/ml, respectively, while recombinant strains harboring C14G and C15G mutations were kanamycin susceptible (MIC, 2.5 to 5 µg/ml). Each of the eis mutants tested remained amikacin susceptible (MIC, 0.5 to 4 µg/ml). The identification of specific eis mutations is needed for accurate genotypic susceptibility testing for kanamycin.