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Amoxicillin resistance in Helicobacter pylori: studies from Tokyo, Japan from 1985 to 2003

Kazuhiro Watanabe1, Akifumi Tanaka, Kyoto Imase

  • 1Third Department of Internal Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan. kazjpgast@nifty.com

Helicobacter
|February 5, 2005
PubMed
Abstract

Insights

Helicobacter pylori (H. pylori) resistance to amoxicillin (AMPC) remains rare in Japan. However, an increase in intermediate resistance suggests potential future rises in AMPC-resistant H. pylori strains.

Area of Science:

  • Medical Microbiology
  • Antimicrobial Resistance
  • Gastroenterology

Background:

  • Amoxicillin (AMPC) is a key component of H. pylori eradication therapy.
  • Previous studies indicated a lack of AMPC-resistant H. pylori strains.
  • The prevalence and evolution of AMPC resistance in Japan were previously unknown.

Purpose of the Study:

  • To determine the prevalence of H. pylori resistance to amoxicillin (AMPC) in Tokyo.
  • To analyze the trends in AMPC resistance from 1985 to 2003.

Main Methods:

  • Tested 648 H. pylori strains isolated from patients with gastrointestinal diseases.
  • Assessed bacterial susceptibility using the E-test and/or Dry-plate method to determine Minimal Inhibitory Concentration (MIC).
  • Defined susceptibility breakpoints: sensitive (AMPC-S; MIC < 0.04 µg/ml), intermediate resistance (AMPC-I; 0.04–1 µg/ml), and resistant (AMPC-R; > 1 µg/ml).

Main Results:

  • No amoxicillin-resistant (AMPC-R) strains were found between 1985 and 1996.
  • Annual resistance rates varied from 1.1% to 8.8% between 1997 and 2003.
  • The proportion of intermediate resistance (AMPC-I) increased from 2000 to 2003.

Conclusions:

  • H. pylori resistance to amoxicillin (AMPC) is currently uncommon in Japan.
  • An increasing trend in intermediate resistance (AMPC-I) was observed.
  • Future increases in amoxicillin-resistant H. pylori strains are possible.

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