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Helicobacter. 1999 Sep;4(3):154-61.

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

Author information

1
Department of Medicine and Pathology, VA Medical Center and Baylor College of Medicine, Houston, TX 77030, USA.

Abstract

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.

PMID:
10469189
[Indexed for MEDLINE]

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