title: Helicobacter pylori-Clarithromycin Resistance in Symptomatic Pediatric Patients in a High Prevalence Country.
abstract: Failure to eradicate Helicobacter pylori despite antibiotic treatment is generally attributed to increasing clarithromycin resistance conferred by point mutations in the 23S-rRNA gene or metronidazole resistance attributed to rdxA gene (HP0954) deletion in patients. Scarce data for pediatric population are available from developing countries.
  
  
  
  The aim of the present study was to determine the presence of A2142G/C and A2143G mutations in the 23S-rRNA gene and/or rdxA gene (HP0954) deletion in a group of symptomatic H pylori-infected children recruited from an area with high infection rate and risk of gastric cancer.
  
  
  
  We recruited 118 patients referred for upper endoscopy for gastrointestinal symptoms. The presence of H pylori was determined by urease test and histological staining. The rdxA gene (HP0954) deletion, and 2142G/C and A2143G mutations were determined by polymerase chain reaction-restriction fragment length polymorphism. A subgroup of infected patients received a 14-day regimen of omeprazole, amoxicillin, and clarithromycin. The effectiveness of this regime was determined by stool antigen determination 8 weeks after treatment.
  
  
  
  About 21% of the analyzed infected patients showed mutation in the 23S-rRNA gene, with the A2143G transition as the more frequent mutation, and 2% of the patients showed rdxA gene (HP0954) deletion. After treatment, 25% of the patients continued to harbor the bacteria; of these, 67% carried the A2143G mutation.
  
  
  
  H pylori-infected pediatric patients from Chile show high prevalence of the mutation responsible for clarithromycin resistance. The failure to eradicate H pylori can be attributed to the presence of the A2143G mutation.
authors.affiliation: Department of Pediatric Gastroenterology and Nutrition, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Carolina A
authors.initials: CA
authors.lastname: Serrano
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Leon
authors.forename: Camila
authors.initials: C
authors.lastname: Palma
authors.forename: Macarena
authors.initials: M
authors.lastname: Vera
authors.forename: Caroll
authors.initials: C
authors.lastname: Hernandez
authors.forename: Paul R
authors.initials: PR
authors.lastname: Harris
mesh_terms: D000293:Adolescent; D054458:Amplified Fragment Length Polymorphism Analysis; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D002677:Chile / Q000453:epidemiology; D017291:Clarithromycin / Q000494:pharmacology* / Q000627:therapeutic use; D003906:Developing Countries; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D005260:Female; D005500:Follow-Up Studies; D016481:Helicobacter Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000494:pharmacology / Q000627:therapeutic use; D009601:Nitroreductases / Q000235:genetics*; D017354:Point Mutation; D012150:Polymorphism, Restriction Fragment Length; D015995:Prevalence; D012338:RNA, Ribosomal, 23S / Q000235:genetics*; D017384:Sequence Deletion; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012338:RNA, Ribosomal, 23S; D008795:Metronidazole; D009601:Nitroreductases; C476646:RdxA protein, Helicobacter pylori; D017291:Clarithromycin