Different penicillin-binding protein profiles in amoxicillin-resistant Helicobacter pylori

Helicobacter. 1999 Sep;4(3):154-61. doi: 10.1046/j.1523-5378.1999.99310.x.


Background: The beta-lactam group of antibiotics kills bacteria by inhibiting the terminal stages of peptidoglycan metabolism. We have recently identified amoxicillin-resistant Helicobacter pylori, none of which expressed beta-lactamase. Penicillin-binding proteins (PBPs) represent a group of target enzymes for the beta-lactam antibiotic family, and alterations in PBPs have been described in other penicillin-resistant bacteria. The amoxicillin-resistant phenotype characteristically was lost after freezing but could be restored by consecutive transfers into gradient plates.

Materials and methods: To determine whether amoxicillin resistance in H. pylori was related to alterations in any of the H. pylori PBPs, five H. pylori strains resistant to amoxicillin and three amoxicillin-sensitive strains were tested. PBPs were extracted from bacteria grown to logarithmic phase, labeled in vivo with 3H-benzylpenicillin, and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography. Four main PBPs were separated from all amoxicillin-sensitive H. pylori strains.

Results: Only three of the four main PBPs were found in the amoxicillin-resistant H. pylori strains. The differentially detectable PBP (PBP D) had an apparent molecular weight of 30 to 32 kD.

Conclusion: These results suggest that PBP D might play a role in the amoxicillin-resistant phenotype of H. pylori strains lacking beta-lactamase activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amoxicillin / pharmacology*
  • Ampicillin Resistance*
  • Bacterial Proteins*
  • Carrier Proteins / analysis*
  • Dyspepsia / microbiology
  • Electrophoresis, Polyacrylamide Gel
  • Helicobacter Infections / microbiology
  • Helicobacter pylori / chemistry*
  • Helicobacter pylori / drug effects*
  • Helicobacter pylori / enzymology
  • Helicobacter pylori / growth & development
  • Hexosyltransferases*
  • Humans
  • Microbial Sensitivity Tests
  • Muramoylpentapeptide Carboxypeptidase / analysis*
  • Penicillin-Binding Proteins
  • Penicillins / pharmacology
  • Peptic Ulcer / microbiology
  • Peptidyl Transferases*
  • beta-Lactamases / metabolism


  • Bacterial Proteins
  • Carrier Proteins
  • Penicillin-Binding Proteins
  • Penicillins
  • Amoxicillin
  • Peptidyl Transferases
  • Hexosyltransferases
  • Muramoylpentapeptide Carboxypeptidase
  • beta-Lactamases