Primary antimicrobial resistance of Helicobacter pylori in children during the past 9 years

Abstract

Antimicrobial resistance of Helicobacter pylori is a growing problem in clinical practice, particularly clarithromycin resistance. The aim of the present study was therefore to investigate the prevalence of H. pylori resistance to antimicrobial agents in Japanese children. A total of 61 H. pylori strains isolated from children (mean age, 12.6 years; range, 4-18 years) between 1999 and 2007 were studied for primary antimicrobial resistance, using a microdilution method. In addition, the eradication rate with lansoprazole-based triple regimens was determined. The overall resistance rate of clarithromycin, amoxicillin and metronidazole was 36.1%, 0% and 14.8%, respectively. Resistance to both clarithromycin and metronidazole was detected in 6.6% of the strains. The rate of clarithromycin-resistant strains was 32.4% from 1999 to 2002 and 40.7% from 2003 to 2007, and clarithromycin minimum inhibitory concentration at which 90% of the isolates were inhibited (MIC(90)) increased fourfold from 1999-2002 to 2003-2007, with all clarithromycin-resistant strains showing low-level resistance. Metronidazole resistance rates were not different between these two study periods. Regimens involving amoxicillin and clarithromycin (n= 49) had a higher eradication rate in clarithromycin-susceptible strains (97.1%) than in the resistant strains (57.1%; P < 0.001). There was no difference in the eradication rate between 7 day and 10 or 14 day courses of the regimens (P= 0.53). The regimen with amoxicillin and metronidazole produced successful eradication in all nine patients with clarithromycin-resistant strains. Clarithromycin resistance of H. pylori is high, and triple regimen treatment containing clarithromycin should be decided based on susceptibility to the agent.