Helicobacter pylori (HP) is the most common pathogen found in humans. Its resistance to clarithromycin is increasing continuously and it is one of the main reasons for eradication failure. The resistance is attributed to three point mutations (PM): A2142G, A2142C and A2143G within the peptidyl-transferase encoding region of the 23S rRNA gene.
We aimed to analyze the predominance of HP clarithromycin resistance by using our novel high resolution melt (HRM) curve assay.
A total of 58 HP stool samples were collected from patients with general gastric discomfort who also performed 13CO2 breath tests (BTs). HP DNA was extracted from the stool and was analyzed by HRM. The results were compared to the BTs. The HRM positive results were further analyzed by comparing them to 4 reference plasmids incorporating the three mutations and the WT sequences.
The HRM results presented 42 positive and 16 negative samples – demonstrating a 66% clarithromycin resistance. When compared to the 37 positive and 21 negative BT, the HRM had a sensitivity of 97% and specificity of 71%. Of the 58 positive HRM samples, 15 (34%) had a WT sequence, 6 (14%) had an A2142G PM, 7 (16%) had an A2142C PM, 11 (25%) had an A2143G PM and 5 (11%) were heterozygote (multiple peaks).
Our study is consistent with other reports suggesting an increasing HP clarithromycin resistance worldwide, yet further investigation is required in order to determine its prevalence in Israel. Moreover, our HRM assay may be used for screening prior to administration of clarithromycin eradication therapy.
