| Purpose Helicobacter pylori (H. pylori) infection is considered as one of themain cause of gastric cancer. Treatment failure of the
infection often occurs due to antibiotic resistance. Herein, we aimed to evaluate the mutations in 23S rRNA gene of H. pylori
which are associated with clarithromycin resistance and in rdxA and frxA genes of the bacterium which may be associated with
metronidazole resistance, in paraffin-embedded gastric biopsies from patients with gastric adenocarcinoma and gastritis in Tabriz,
the northwest of Iran.
Methods In the study, 80 paraffin-embedded tissue sections from 40 gastric cancer and 40 gastritis patients in the Imam Reza
hospital, Tabriz, Iran were collected. The existence of ureC gene was verified by PCR method. Genotypical clarithromycin
resistance was investigated by real-time PCR method and determination of the melting temperature. PCR reaction and sequencing
were used for the evaluation of mutations in rdxA and frxA genes.
Results The results of ureC amplification showed that DNA of H. pylori was present in the 82.66% of the obtained DNA
samples. About 45.16% of samples were resistant to the clarithromycin and 53.22% of them were resistant to the metronidazole.
Based on the results from real-time PCR, the frequency of mutations was as follow A2143G 64.28%, A2142G 44.44% and
A2142C 1.11%. The mutations of rdxA gene were 66.66% missense, 30.30% frameshift and 3.03% non-sense. The mutations of
frxA gene were 36.36% missense, 54.54% frameshift and non-sense 9.09%.
Conclusion A2143G mutation is the most frequent mutation among clarithromycin resistant genes in Iran. Also, missense and
frameshift mutations are frequent in rdxA and frxA genes. Screening for these mutations could help researchers to investigate the
most effective anti-H. pylori antibiotics and to prevent antibiotic resistance. |