Premium
Multiple Mutations in or Adjacent to the Conserved Penicillin‐Binding Protein Motifs of the Penicillin‐Binding Protein 1A Confer Amoxicillin Resistance to Helicobacter pylori
Author(s) -
Gerrits Monique M.,
Godoy Anita P. O.,
Kuipers Ernst J.,
Ribeiro Marcelo L.,
Stoof Jeroen,
Mendonça Sergio,
Van Vliet Arnoud H. M.,
Pedrazzoli José,
Kusters Johannes G.
Publication year - 2006
Publication title -
helicobacter
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.206
H-Index - 79
eISSN - 1523-5378
pISSN - 1083-4389
DOI - 10.1111/j.1523-5378.2006.00398.x
Subject(s) - penicillin binding proteins , penicillin , amoxicillin , helicobacter pylori , microbiology and biotechnology , mutation , genetics , chemistry , antibiotics , biology , gene
Background: Amoxicillin‐based therapies are highly effective for the treatment of Helicobacter pylori infections, but the efficacy may decrease as the incidence of amoxicillin resistance is increasing. So far, the molecular mechanism underlying stable amoxicillin resistance has only been identified for a few naturally occurring amoxicillin‐resistant (Amx R ) H. pylori isolates, and is mediated by mutations in penicillin‐binding protein 1A (PBP1A). In this study the molecular mechanism underlying amoxicillin resistance of seven additional Amx R H. pylori isolates has been established. Methods: H. pylori strain 26695 (minimal inhibitory concentration (MIC) 0.125 mg/l) was naturally transformed with total DNA and pbp1A polymerase chain reaction (PCR) products from the seven Amx R H. pylori isolates, and the MIC of amoxicillin and pbp1A gene sequence of the obtained Amx R transformants were determined. Results: Replacement of the wild‐type pbp1A gene of H. pylori reference strain 26695 by the pbp1A gene of the Amx R H. pylori isolates resulted in an increased MIC (0.5–1.0 mg/l). Sequence analysis of the smallest PBP1A fragments able to transfer the resistance indicated that several amino acid substitutions in or adjacent to the second (SKN 402−404 ) and third (KTG 555−557 ) conserved penicillin‐binding protein motifs (PBP‐motifs) mediate amoxicillin resistance in H. pylori . This was confirmed by site‐directed mutagenesis using oligonucleotides that contained defined mutations in or adjacent to these PBP‐motifs. Conclusion: In naturally occurring Amx R H. pylori isolates, amoxicillin resistance is mediated by various mutational changes located in or adjacent to the second and third PBP‐motifs of the PBP1A. Although we cannot exclude the role of the other genes in amoxicillin resistance, it is likely that multiple mutational changes in the PBP1A gene are the predominant cause of amoxicillin resistance in H. pylori . The findings of this study currently preclude the rapid detection of amoxicillin resistance in H. pylori by molecular tests.