Hays C, et al. - Here, the experts assess the rate of rifamycins resistance and determine the mutations in the rpoB gene conferring resistance to discuss the current breakpoint. The classification of Helicobacter pylori isolates as resistant to rifampicin (RP) is proposed for MICs > 4 mg/L. They consider that ≥0.125 mg/L is the optimal cut off for rifabutin (RB). Findings describe a new mutation responsible for rifamycins, resistance, L547F.