title: High rates of recurrence and of transient reinfections of Helicobacter pylori in a population with high prevalence of infection.
abstract: OBJECTIVE
  Little is known concerning the magnitude of reinfection versus recrudescence of Helicobacter pylori (H. pylori) infection after eradication treatment. The aims of this study were to determine the magnitude of H. pylori reinfection versus recrudescence, and to identify possible risk factors for reinfection.
  
  
  METHODS
  Children and adults with upper GI symptoms treated at the Centro Médico Nacional Siglo XXI (Instituto Mexicano del Seguro Social, in Mexico City, Mexico) were studied. H. pylori infection was diagnosed with urea breath test (UBT), histology, and culture. Infected patients received triple therapy, and those who became UBT negative 4-6 wk after treatment were considered as eradicated and were included in the study. A cohort of 141 patients in whom the disease was eradicated was monitored for recurrence with UBT at 3, 6, 9, 12, 18, and 24 months. H. pylori was isolated from gastric biopsy samples before treatment and at recurrence and isolates compared by genotyping.
  
  
  RESULTS
  During this period, 32 (22.7%) cases of recurrence were documented the majority occurring during yr 1. In nine of the 32 (28.1%) cases, recurrence was eradicated spontaneously, suggesting these were transient reinfections. Recurrence rates were significantly higher in the subjects 41-60 yr of age than in younger or older subjects. H. pylori isolates from 12 recurrence cases were genotyped; nine (75%) were classified as true reinfection and three as recrudescence.
  
  
  CONCLUSIONS
  In our population, recurrence rate is high in adults and transient reinfection is common. In several cases, reinfection occurred by multiple strains, which suggests that soon after eradication, patients are exposed to multiple sources of reinfection.
authors.affiliation: Unidad de Investigación en Enfermedades Infecciosas, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, México City, México.
authors.forename: Yelda
authors.initials: Y
authors.lastname: Leal-Herrera
authors.forename: Javier
authors.initials: J
authors.lastname: Torres
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Monath
authors.forename: Irma
authors.initials: I
authors.lastname: Ramos
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gomez
authors.forename: Armando
authors.initials: A
authors.lastname: Madrazo-de la Garza
authors.forename: Margarita
authors.initials: M
authors.lastname: Dehesa-Violante
authors.forename: Onofre
authors.initials: O
authors.lastname: Muñoz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000890:Anti-Infective Agents / Q000627:therapeutic use; D001707:Biopsy, Needle; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D016001:Confidence Intervals; D004269:DNA, Bacterial / Q000032:analysis; D019353:Endemic Diseases; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D016481:Helicobacter Infections / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D016480:Helicobacter pylori / Q000187:drug effects / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D011336:Probability; D012008:Recurrence; D018570:Risk Assessment; D012720:Severity of Illness Index
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial