Characterization of clarithromycin resistance in isolates of Helicobacter pylori from the UAE.

Background: Clarithromycin therapy is effective in eradicating Helicobacter pylori. However, the resistance of H. pylori to clarithromycin is increasingly reported. The present study aimed to characterize the types of mutations present in the 23S rRNA genes of isolates of clarithromycin-resistant H. pylori from the UAE.

Methods: Clarithromycin susceptibility of H. pylori isolates (n = 26) was determined by E tests. Analyses for point mutations in domain V of the 23S rRNA genes in clarithromycin-resistant and-sensitive strains were performed by sequence analysis of amplified PCR products.

Results: Out of 100 gastric antral biopsy samples, 26 were positive for H. pylori by culture, and 29 were positive by PCR. Of the 26 culture isolates, five (19.2%) were resistant to clarithromycin and 24 were sensitive. The MIC of the resistant strains ranged from 3 to 24 microg/mL (median 24). All of the clarithromycin-resistant isolates had point mutations in the 23S rRNA gene. Two isolates had an A2142G 23S rRNA mutation, and three had A2143G mutations.

Conclusion: Clarithromycin resistance was common in this small collection of H. pylori isolates from the UAE. The A2142G and A2143G mutations were associated with clarithromycin resistance.