Rapid screening of clarithromycin resistance in Helicobacter pylori by pyrosequencing.

Helicobacter pylori infections can be effectively treated with clarithromycin, a macrolide, in combination with other antibiotics, such as amoxicillin, tetracycline or metronidazole. The failure of H. pylori eradication is mainly associated with macrolide-resistant strains. Three point mutations (A2142G/C, A2143G, T2182C) in the peptidyltransferase region of domain V of the 23S rRNA have been described as being associated with clarithromycin resistance. Therefore, the determination of clarithromycin resistance by pyrosequencing was evaluated. H. pylori from 81 gastric biopsies was cultured and clarithromycin resistance was determined by Etest, as well as by pyrosequencing technology (PSQ 96 system; Biotage). The respective mutations were set in relation to the MIC measured in microg ml(-1) by Etest. In this study, point mutations in positions 2142 and 2143 were associated with clarithromycin resistance. Mutations in position 2182 did not contribute to clarithromycin resistance. In addition, from 22 out of the 81 biopsies, clarithromycin resistance was determined directly without culturing H. pylori to save additional time. Identical results were obtained as compared to resistance testing with pure H. pylori strains. All results obtained by pyrosequencing were evaluated by Sanger sequencing. The data show that pyrosequencing to detect point mutation is a fast and reliable method for determining clarithromycin resistance in H. pylori, and provides the same results as the Etest.