Second-line treatment of Helicobacter pylori infection after dilution agar methods and PCR-RFLP analysis.
BACKGROUND
After unsuccessful first-line treatment of Helicobacter pylori infection, the percentage of clarithromycin-resistant strains has been reported as between 30% and 70% in Japan and other countries. A high prevalence of clarithromycin-resistant strains is reported to be associated with eradication failure.


OBJECTIVE
We examined antibiotic susceptibility testing using a combination of dilution agar methods with PCR-restriction fragment length polymorphism (RFLP) analysis.


METHODS
We enrolled 41 patients in whom first-line treatment with LAC (lansoprazole, amoxycillin and clarithromycin) was unsuccessful. Endoscopic biopsied specimens were used to examine antibiotic susceptibility to clarithromycin by dilution agar methods. PCR-RFLP analysis was performed to determine the presence of point mutations, which are primarily responsible for resistance to clarithromycin.


RESULTS
Clarithromycin-resistance rate after failure of the LAC regimen was 73.2%. Drug susceptibilities of three strains obtained by PCR-RFLP analysis were different from those by dilution agar methods. One strain with MIC values to clarithromycin of 0.05 micro g/mL had a point mutation, A2144G. This strain was not eradicated by repeating LAC, but was eradicated by substituting metronidazole for clarithromycin.


CONCLUSIONS
Dilution agar methods should be combined with PCR-RFLP analysis before second-line eradication to increase the accuracy of clarithromycin-susceptibility testing and to improve eradication efficacy.
Masaoka
T
T
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
SuzukiKurabayashi
H K
HK
Kamiya
A G
AG
Ishii
H
H
D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000627:therapeutic use; D017291:Clarithromycin / Q000627:therapeutic use; D015169:Colony Count, Microbial / Q000379:methods; D004269:DNA, Bacterial / Q000032:analysis; D024881:Drug Resistance, Bacterial; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D005260:Female; D005756:Gastritis / Q000382:microbiology; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000235:genetics; D016480:Helicobacter pylori / Q000235:genetics*; D006801:Humans; D064747:Lansoprazole; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009853:Omeprazole / Q000031:analogs & derivatives* / Q000627:therapeutic use; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D013276:Stomach Ulcer / Q000382:microbiology; D016896:Treatment Outcome
D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D004269:DNA, Bacterial; D064747:Lansoprazole; D000658:Amoxicillin; D017291:Clarithromycin; D009853:Omeprazole