Prevalence and antimicrobial resistance of highly virulent cagA-positive Helicobacter pylori strains in Southern Poland

Assessment of Helicobacter pylori (H. pylori) prevalence in Southern Poland, focusing on highly virulent cagA-positive strains associated with gastric cancer risk, along with analysis of antimicrobial resistance and its molecular mechanisms.

A total of 130 dyspeptic patients, who underwent endoscopy, were enrolled in the study. Presence of H. pylori in gastric mucosa biopsy specimens was confirmed by rapid urease tests, histological examination, culture, and molecular assays. Antimicrobial susceptibility was tested using the E-test, while the cagA gene (virulence marker) was identified by PCR. The GenoType HelicoDR detected mutations for resistance to clarithromycin (23 S rRNA) and levofloxacin (gyrA). Resistance to rifampicin and levofloxacin was investigated by sequencing the rpoB and gyrA genes.

H. pylori prevalence in Southern Poland was 30.8%, with 60% of infections involving cagA-positive strains. Susceptibility testing revealed resistance rates of 22.9% for metronidazole, 14.3% for clarithromycin, 11.4% for levofloxacin and 25.7% for rifampicin. Among the 24 cagA-positive strains, 45.8% were resistant to at least one antibiotic. Clarithromycin resistance was caused by A2143G mutation. The gyrA gene sequence showed the N87K mutation linked to fluoroquinolone resistance. No mutations were found in the rpoB gene.

Infections with multidrug-resistant CagA-positive strains require recommended treatment strategies due to the high risk of progression of infection to gastric cancer.