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Amoxycillin tolerance in Helicobacter pylori
M P Dore1, M S Osato, G Realdi
1VA Medical Center and Baylor College of Medicine, Houston, TX 77030, USA.
The Journal of Antimicrobial Chemotherapy
|June 25, 1999
Summary
Amoxycillin resistance in Helicobacter pylori is confirmed, with strains showing tolerance to the antibiotic. Testing minimum bactericidal concentration (MBC) is crucial for identifying tolerance in treatment failures.
Area of Science:
- Microbiology
- Antimicrobial Resistance
Background:
- Recent reports indicate emerging amoxycillin resistance in Helicobacter pylori.
- Understanding amoxycillin resistance and tolerance is critical for effective H. pylori eradication therapy.
Purpose of the Study:
- To demonstrate amoxycillin resistance in H. pylori.
- To investigate amoxycillin tolerance in resistant H. pylori strains.
Main Methods:
- Studied 17 amoxycillin-resistant and 4 amoxycillin-sensitive H. pylori strains.
- Assessed amoxycillin resistance and tolerance using Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays.
- Investigated the stability of amoxycillin resistance through strain storage and rescue experiments.
Main Results:
- Primary H. pylori isolates exhibited amoxycillin resistance without detectable beta-lactamase activity.
- Amoxycillin resistance was lost upon storage but could be restored.
- MBC/MIC ratios ranged from 32 to >1024, indicating significant amoxycillin tolerance.
Conclusions:
- Amoxycillin resistance is a validated phenomenon in H. pylori.
- H. pylori strains can exhibit tolerance to amoxycillin, characterized by high MBC/MIC ratios.
- Determination of MBC alongside MIC is recommended for H. pylori susceptibility testing in patients with treatment failure to detect tolerance.