Long-term persistence of resistant Enterococcus species after antibiotics to eradicate Helicobacter pylori

Ann Intern Med. 2003 Sep 16;139(6):483-7. doi: 10.7326/0003-4819-139-6-200309160-00011.


Background: Antibiotic treatment selects for resistance not only in the pathogen to which it is directed but also in the indigenous microflora.

Objective: To determine whether a widely used regimen (clarithromycin, metronidazole, and omeprazole) for Helicobacter pylori eradication affects resistance development in enterococci.

Design: Cohort study.

Setting: Endoscopy units at 3 community hospitals in Sweden.

Patients: 5 consecutive dyspeptic patients who were colonized with H. pylori, had endoscopy-confirmed duodenal ulcer, and received antibiotic treatment, and 5 consecutive controls with dyspepsia but no ulcer who did not receive treatment.

Measurements: Fecal samples were obtained from patients and controls before, immediately after, 1 year after, and 3 years after treatment. From each patient and sample, enterococci were isolated and analyzed for DNA fingerprint, clarithromycin susceptibility, and presence of the erm(B) gene.

Results: In treated patients, all enterococci isolated immediately after treatment showed high-level clarithromycin resistance due to erm(B). In 3 patients, resistant enterococci persisted for 1 to 3 years after treatment. No resistance developed among controls.

Conclusion: A common H. pylori treatment selects for highly resistant enterococci that can persist for at least 3 years without further selection.

Publication types

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

MeSH terms

  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use*
  • Anti-Ulcer Agents / therapeutic use
  • Clarithromycin / therapeutic use
  • Drug Resistance, Bacterial*
  • Drug Therapy, Combination
  • Duodenal Ulcer / drug therapy
  • Duodenal Ulcer / microbiology
  • Enterococcus / drug effects*
  • Female
  • Helicobacter Infections / drug therapy*
  • Helicobacter Infections / microbiology
  • Helicobacter pylori*
  • Humans
  • Male
  • Metronidazole / therapeutic use
  • Middle Aged
  • Omeprazole / therapeutic use
  • Prospective Studies


  • Anti-Bacterial Agents
  • Anti-Ulcer Agents
  • Metronidazole
  • Clarithromycin
  • Omeprazole