Mutations in the beginning of the rpoB gene can induce resistance to rifamycins in both Helicobacter pylori and Mycobacterium tuberculosis

A clinical isolate of Helicobacter pylori that developed resistance to rifa butin during therapy carried an rpoB gene that retained a wild-type cluster region sequence but had acquired a novel codon 149 (V149F) mutation. In tr ansformation experiments, the mutation was shown to confer high-level rifab utin resistance. The equivalent mutation (V176F) was present in several res istant isolates of Mycobacterium tuberculosis.