Second‐line treatment of Helicobacter pylori infection after dilution agar methods and PCR‐RFLP analysis

• Published in: Alimentary pharmacology & therapeutics Vol. 20; no. s1; pp. 68 - 73
• Main Authors: Masaoka, T., Suzuki Kurabayashi, H., K., Kamiya, A. G., Ishii, H.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2004
• Subjects: 2-Pyridinylmethylsulfinylbenzimidazoles; Adult; Aged; Amoxicillin - therapeutic use; Clarithromycin - therapeutic use; Colony Count, Microbial - methods; DNA, Bacterial - analysis; Drug Resistance, Bacterial; Drug Therapy, Combination - therapeutic use; Female; Gastritis - microbiology; Helicobacter Infections - drug therapy; Helicobacter Infections - genetics; Helicobacter pylori - genetics; Humans; Lansoprazole; Male; Microbial Sensitivity Tests; Middle Aged; Omeprazole - analogs & derivatives; Omeprazole - therapeutic use; Point Mutation; Polymerase Chain Reaction - methods; Polymorphism, Restriction Fragment Length; Stomach Ulcer - microbiology; Treatment Outcome
• ISSN: 0269-2813; 1365-2036
• DOI: 10.1111/j.1365-2036.2004.01994.x

Summary 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. Aim : 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 µg/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.