Detection of antimicrobial resistance genes of Helicobacter pylori strains to clarithromycin, metronidazole, amoxicillin and tetracycline among Egyptian patients

Abstract

Background: Antibiotic resistance of Helicobacter pylori (H. pylori) treatment is on the rise, and is affecting the efficacy of current used therapeutic regimens.

Aim: We aimed to enhance the understanding of antimicrobial resistance rates of H. pylori strains recovered from patients at Theodor Bilharz Research Institute Hospital in Egypt, as a mandatory step before starting treatment.

Subjects and methods: Mutant genes conferring metronidazole, amoxicillin, clarithromycin, and tetracycline resistance were detected in 60 H. pylori strains recovered from patients who underwent upper endoscopic examination. Patients were considered to be infected with H. pylori when rapid urease test and detection of 16S rRNA in gastric biopsies recorded positive. Molecular detection of resistant genes to metronidazole (rdx gene) and amoxicillin (pbp1A gene) was carried out by conventional PCR followed by sequencing of PCR products. While detection of 23S rRNA gene conferring clarithromycin resistance and detection of 16S rRNA mutation gene conferring tetracycline resistance were carried out by realtime PCR.

Results:  H. pylori resistance rates to metronidazole, and amoxicillin were 25% and 18.3% respectively. While for clarithromycin and tetracycline, point mutations in 23S rRNA types A2142G and A2143G and in 16S rRNA of H. pylori were assessed by real time PCR assay respectively. Resistance mutant genes were found to be 6.7% of clarithromycin and 1.7% of tetracycline. Combined resistance rates to metronidazole and amoxicillin was (11.6%) followed by metronidazole and clarithromycin (5%), while patterns of clarithromycin and amoxicillin (1.6%), metronidazole, clarithromycin and amoxicillin (1.6%) were revealed.

Conclusion: Data concerning antimicrobial resistance genes play an important role in empiric treatment of H. pylori infection. According to our results, H. pylori resistance to metronidazole and amoxicillin was relatively high. Clarithromycin is still a good option for first line anti-H. pylori treatment. Combined resistant strains are emerging and may have an effect on the combination therapy.

Keywords: H. pylori, Antimicrobial resistance, Gene mutations, Rdx gene, Clarithromycin resistance, Tetracycline resistance