Clarithromycin Resistance in Helicobacter pylori Strains Isolated from French Children: Prevalence of the Different Mutations and Coexistence of Clones Harboring Two Different Mutations in the Same Biopsy

Abstract

The aim of our study was to assess the different mutations involved in clarithromycin-resistant Helicobacter pylori strains isolated from French children and their temporal trends. The point mutations of H. pylori were detected by PCR followed by RFLP technique in 50 clarithromycin-resistant strains collected between 1993 and 2004 in France. Clarithromycin resistance was observed in 23% (50/217) of H. pylori isolates. Two mutations A2143G and A2142G in the 23S rRNA genes of H. pylori were detected. The former was found in 45/50 (90%) of isolates. The rate of resistance increased with time from 18.6% in the period 1993-1996 to 41.6% in 2001-2004. No significant difference was observed in the distribution of mutations during the same periods. No correlation was found between any mutation and age, sex, and ethnic origin of children. Furthermore, no significant differences in minimal inhibitory concentrations level were observed according to the different point mutations. In all cases, only one point mutation was present, except in two cases where two different mutations were found in two different clones from the same biopsy. The mutation A2143G is predominant in clarithromycin-resistant H. pylori strains isolated from children in France. We report for the first time the presence of two clarithromycin-resistant clones harboring two different mutations of the 23S rRNA genes present in the same biopsy specimen and genotypically identical as demonstrated by RAPD fingerprinting.