Antibiotic resistance of Helicobacter pylori strains in Japanese children - PubMed (original) (raw)

Antibiotic resistance of Helicobacter pylori strains in Japanese children

Seiichi Kato et al. J Clin Microbiol. 2002 Feb.

Abstract

The resistance of Helicobacter pylori to the recently available antibiotic treatment regimens has been a growing problem. We investigated the prevalence of H. pylori resistance to clarithromycin, metronidazole, and amoxicillin among 51 H. pylori isolates from Japanese children. In addition, the mutations of the corresponding gene were studied by PCR and restriction fragment length polymorphism analysis. Primary resistance to clarithromycin, metronidazole, and amoxicillin was detected in 29, 24, and 0% of strains, respectively. The eradication rates in clarithromycin-susceptible and -resistant strains were 89 and 56%, respectively (P < 0.05). The prevalence of strains with acquired resistance to clarithromycin (78%) was higher than that of strains with primary resistance (P < 0.01). Among the clarithromycin-resistant strains studied, 92% showed cross-resistance to azithromycin. No acquired resistance to amoxicillin was demonstrated. The A2144G mutation in the 23S rRNA gene was detected in 11 of 12 (92%) clarithromycin-resistant strains tested, whereas the mutation was not detected in any of the 15 susceptible strains. The deletion of the rdxA gene was not demonstrated in any of the strains. The results indicate that a high prevalence of clarithromycin-resistant strains is associated with eradication failure. Testing of susceptibility to clarithromycin is recommended.

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Figures

FIG. 1.

FIG. 1.

Distribution of antibiotic MICs for 51 H. pylori strains. In the present study, resistance breakpoints for clarithromycin, metronidazole, and amoxicillin were defined as ≥1.0, >8, and >0.5 μg/ml, respectively.

FIG. 2.

FIG. 2.

Restriction endonuclease analysis of 23S rRNA amplicons. (A) Digestion with _Bsa_I; (B) digestion with _Mbo_II. Lanes 1 to 5, clarithromycin-resistant H. pylori strains for which MICs are 8, 4, 2, 1, and 4 μg/ml, respectively; lanes 6, clarithromycin-susceptible H. pylori strain for which the MIC is <0.015 μg/ml; lanes M, DNA size markers (the numbers between the panels are in base pairs). The A2144G mutation was found in lanes 1 to 4 but was not found in lane 5. Note that the A2143G mutation detected by digestion with _Mbo_II was not detected in any of the strains studied.

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