Sequence Polymorphism in the rrs Gene of Mycobacterium tuberculosis Is Deeply Rooted within an Evolutionary Clade and Is Not Associated with Streptomycin Resistance

A mutation (C-to-T transition) at position 491 of the rrs gene was identified in a Mycobacterium tuberculosis strain family (n = 208 isolates) that was predominant in a suburb of Cape Town, South Africa. This nucleotide change is not involved in streptomycin resistance, and we suggest caution in assuming that all mutations in genes targeted by antituberculosis drugs confer drug resistance.