Molecular characterisation and mutational analysis of antimicrobial resistance genes in Helicobacter pylori isolates in Erbil, Iraq.

BACKGROUND

Antibiotic resistance in Helicobacter pylori poses a significant challenge to the effective eradication of infection worldwide. Understanding molecular mechanisms of resistance is essential for guiding treatment strategies. This study aimed to investigate the molecular basis of antimicrobial resistance in Helicobacter pylori isolates and their associated mutation frequencies.

METHODS

In this cross-sectional study, gastric biopsy specimens were collected from 203 patients at Rizgary Hospital in Erbil, Kurdistan Region, Iraq, who underwent endoscopy for dyspepsia-related symptoms. Of the 137 positive patients, 91 Helicobacter pylori isolates were confirmed by colony morphology, Gram staining, and biochemical tests; 63 were successfully subcultured for antimicrobial susceptibility testing (culture success rate: 69.2%). Antimicrobial susceptibility testing was performed by the agar dilution method to determine the minimum inhibitory concentrations. The sequences of specific genes were examined and analysed by next-generation sequencing. Multiple sequence comparisons were performed to identify resistance-related genes and mutations, using 26695 (NC_000915.1) as the reference genome.

RESULTS

Only two isolates (3.17%) were susceptible to all antibiotics examined. The frequency of metronidazole resistance was highest (85.71%), followed by levofloxacin (55.55%), clarithromycin (52.38%), amoxicillin (26.98%), tetracycline (6.35%), and rifabutin (4.76%). Mutations in the rdxA and frxA genes correlated with metronidazole resistance, while GyrA protein mutations at positions 87 and 91 were linked to levofloxacin resistance. Clarithromycin resistance was mainly associated with A2142G and A2143G mutations in 23S rRNA. Amoxicillin resistance (26.98%) was associated with mutations in the pbp1A gene, whereas resistance to tetracycline and rifabutin was infrequent.

CONCLUSIONS

This study provides the first molecular surveillance data on antimicrobial resistance in Helicobacter pylori in northern Iraq, offering valuable regional evidence to guide local eradication strategies. The relatively high amoxicillin resistance, together with the elevated resistance to metronidazole, levofloxacin, and clarithromycin, underscores the need for susceptibility-guided therapy and continuous local antimicrobial resistance surveillance.