title: Reinfection rate of Helicobacter pylori after eradication treatment: a long-term prospective study in Japan.
abstract: BACKGROUND
  We previously reported that the reinfection rate with Helicobacter pylori in Japan was low despite a high prevalence of infection. In the present study, we extended our previous work to more accurately determine the reinfection rate.
  
  
  METHODS
  We enrolled 1625 patients (219 women and 1406 men, mean age 50.8 years) who had received H. pylori eradication therapy. After documentation of eradication, bacterial culture and urea breath test were carried out yearly. H. pylori strains were analyzed by using random amplification of polymorphic DNA fingerprinting.
  
  
  RESULTS
  A total of 1609 patients were followed for up to 12.5 years (mean 4.7 years); H. pylori became re-positive in 26 patients. In 13 of the 26 patients, H. pylori became positive at the first-year follow up. Stored H. pylori isolates were available for analysis from ten of the 13 patients; four of the isolates were genetically different from the initial strain, but the other six were identical to the initial strain. In the other 13 patients, H. pylori became positive at later follow up (mean 4.8 years; range 1.8-8.0 years). In all of the four of these patients whose isolates could be analyzed, the H. pylori strains were different from the initial strain. Assuming that reinfection occurred in the four patients positive for different strains of H. pylori at the first-year follow up and in the 13 positive at later follow up, the reinfection rate was 0.22% per year.
  
  
  CONCLUSIONS
  When probable recrudescence (H. pylori positivity with identical strains) was excluded, the reinfection rate of H. pylori in this Japanese population was very low, but we note that reinfection can occur over many years.
authors.affiliation: Department of Internal Medicine, Fukuwatari Municipal Hospital, Okayama, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Take
authors.forename: Motowo
authors.initials: M
authors.lastname: Mizuno
authors.forename: Kuniharu
authors.initials: K
authors.lastname: Ishiki
authors.forename: Takayuki
authors.initials: T
authors.lastname: Imada
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Okuno
authors.forename: Tomowo
authors.initials: T
authors.lastname: Yoshida
authors.forename: Kenji
authors.initials: K
authors.lastname: Yokota
authors.forename: Keiji
authors.initials: K
authors.lastname: Oguma
authors.forename: Masahide
authors.initials: M
authors.lastname: Kita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okada
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D015373:Bacterial Typing Techniques; D001944:Breath Tests / Q000379:methods; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D005500:Follow-Up Studies; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D016480:Helicobacter pylori / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial