Comparison of new and classical point mutations associated with clarithromycin resistance in Helicobacter pylori strains isolated from dyspeptic patients and their effects on phenotypic clarithromycin resistance.

We aimed to investigate the presence of three recently identified point mutations (A2115G, G2141A and A2144T) of the 23 S rRNA gene and compare them with the three most frequently encountered point mutations (A2142G, A2142C and A2143G) in Helicobacter pylori strains in Turkey. A total of 63 patients (mean 47.08±12.27) were included. The E-test method (for clarithromycin) was used for the clarithromycin antimicrobial susceptibility test of isolated H. pylori strains. Real-time PCR was used to detect the point mutations. A total of 24 out of 63 H. pylori strains (38.1%) were detected as clarithromycin resistant (>0.5 mg l We concluded that classical mutations of the 23 S rRNA gene resulted in higher clarithromycin MIC values than new mutations. These new point mutations caused moderate elevations in the MIC values of clarithromycin-resistant H. pylori strains.