Mutations of the Helicobacter pylori genes rdxA and pbp1 cause resistance against metronidazole and amoxicillin

To investigate amoxicillin and metronidazole resistance of Helicobacter pyl ori, we compared putative resistance genes between resistant strains obtain ed in vitro and their sensitive parent strain. All metronidazole-resistant strains had rdxA mutations, and an amoxicillin-resistant strain had pbp1 an d pbp2 mutations. By transforming PCR products of these mutated genes into antibiotic-sensitive strains, we showed that rdxA null mutations were suffi cient for metronidazole resistance, while pbp1 mutations contributed to amo xicillin resistance of H, pylori.