title: Mechanism of metronidazole resistance in Helicobacter pylori: comparison of the rdxA gene sequences in 30 strains.
abstract: The rdxA gene of 30 independently isolated Helicobacter pylori strains was sequenced. A comparison of the rdxA sequences revealed a higher percentage of amino acid substitutions in the corresponding protein than in other housekeeping genes. Out of 122 point mutations, 41 were missense and 4 were nonsense. A resistant strain with a nucleotide insertion in the rdxA sequence was also found. With the exception of the point mutations and the insertion generating a stop signal, no particular nucleotide mutation or amino acid substitution could be associated to metronidazole resistance. Moreover, phylogenetic analysis of the 30 nucleotide sequences did not demonstrate specific clusters associated with the resistance phenotype.
authors.affiliation: Istituto Cantonale Batteriosierologico, 6904 Lugano, Switzerland.
authors.forename: N M
authors.initials: NM
authors.lastname: Solcà
authors.forename: M V
authors.initials: MV
authors.lastname: Bernasconi
authors.forename: J C
authors.initials: JC
authors.lastname: Piffaretti
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics; D016480:Helicobacter pylori / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008565:Membrane Proteins / Q000145:classification / Q000235:genetics*; D008795:Metronidazole / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017354:Point Mutation; D017386:Sequence Homology, Amino Acid
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008565:Membrane Proteins; D008795:Metronidazole; C077236:RdxA protein, Rhodobacter sphaeroides