Gastric microbiome changes in relation with Helicobacter pylori resistance.

Introduction: Inadequate antimicrobial treatment has led to multidrug-resistant (MDR) bacteria, including Helicobacter pylori (H. pylori), which one of the notable pathogens in the stomach. Antibiotic-induced changes in the microbiota can negatively affect the host. This study aimed to determine the influence of H. pylori resistance on the diversity and abundance of the stomach microbiome.

Methods: Bacterial DNA was extracted from biopsy samples of patients presenting dyspepsia symptoms with H. pylori positive from cultures and histology. DNA was amplified from the V3-V4 regions of the 16S rRNA gene. In-vitro E-test was used to detect antibiotic resistance. Microbiome community analysis was conducted through α-diversity, β-diversity, and relative abundance.

Results: Sixty-nine H. pylori positive samples were eligible after quality filtering. Following resistance status to five antibiotics, samples were classified into 24 sensitive, 24 single resistance, 16 double resistance, 5 triple resistance. Samples were mostly resistant to metronidazole (73.33%; 33/45). Comparation of four groups displayed significantly elevated α-diversity parameters under the multidrug resistance condition (all P <0.05). A notable change was observed in triple-resistant compared to sensitive (P <0.05) and double-resistant (P <0.05) groups. Differences in β-diversity by UniFrac and Jaccard were not significant in terms of the resistance (P = 0.113 and P = 0.275, respectively). In the triple-resistant group, the relative abundance of Helicobacter genera was lower, whereas that of Streptococcus increased. Moreover, the linear discriminant analysis effect size (LEfSe) was associated with the presence of Corynebacterium and Saccharimonadales in the single-resistant group and Pseudomonas and Cloacibacterium in the triple-resistant group.

Conclusion: Our results suggest that the resistant samples showed a higher trend of diversity and evenness than the sensitive samples. The abundance of H. pylori in the triple-resistant samples decreased with increasing cohabitation of pathogenic bacteria, which may support antimicrobial resistance. However, antibiotic susceptibility determined by the E-test may not completely represent the resistance status.