title: Association of antibiotic resistance and higher internalization activity in resistant Helicobacter pylori isolates.
abstract: OBJECTIVE
  Helicobacter pylori resistance to antibiotics is the main factor for therapy failure, while other features remain largely unknown. The aims of this study are to investigate the relationship of antibiotic resistance and in vitro internalization activity between cure and failure isolates and to determine whether failures are associated with persistence of the same predominant strain.
  
  
  METHODS
  Fifty-three isolates from forty-seven patients (cure group, n = 31; failure group, n = 16) receiving one of two lansoprazole-based therapies before and/or after therapy were investigated. Antibiotic susceptibility was determined by Etest. Genotyping was determined by cagA, babA, vacA and RAPD analyses. Target cells of internalization assay were AGS cells.
  
  
  RESULTS
  Five of six paired pre- and post-treatment isolates had the same predominant genetic profiles and exhibited similarly high internalization activities. The A2143G point mutation of the 23S rRNA gene conferred clarithromycin resistance. Moreover, increased antibiotic resistance after therapy was found for these five cases. Pre-treatment isolates from the failure group (n = 11) had higher level of internalization activity than those from the cure group (n = 31) (P = 0.00005). Antibiotic-resistant strains were significantly associated with higher internalization activity than were susceptible strains (metronidazole, P < 0.005; clarithromycin, P < 0.005).
  
  
  CONCLUSIONS
  Our results suggest that resistant H. pylori strains are associated with antibiotic resistance and superior internalization activity, protecting them against antibiotic treatment.
authors.affiliation: Institute of Molecular and Cellular Biology & Department of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Chih-Ho
authors.initials: CH
authors.lastname: Lai
authors.forename: Chun-Hsien
authors.initials: CH
authors.lastname: Kuo
authors.forename: Pei-Yu
authors.initials: PY
authors.lastname: Chen
authors.forename: Sek-Kwong
authors.initials: SK
authors.lastname: Poon
authors.forename: Chi-Sen
authors.initials: CS
authors.lastname: Chang
authors.forename: Wen-Ching
authors.initials: WC
authors.lastname: Wang
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008826:Microbial Sensitivity Tests; D017211:Treatment Failure
chemical_list: D000900:Anti-Bacterial Agents