Dinka Ivulic, Camila Cabrera, Felipe Del Canto, Alejandra Gallardo, Anne Lagomarcino, Tomeu Viver, Francisco Alliende, Marcela Toledo, Gabriela Román, Francisca Jaime, Mónica González, Pamela Marchant, Marianela Rojas, Daniel Pizarro, Juan Ignacio Juanet, Mónica Villanueva, Juan Cristobal Ossa, Leandro J Carreno, Miguel O'Ryan, Yalda Lucero
H. pylori-positive patients exhibited a significant reduction in microbial diversity, a higher dominance index primarily due to H. pylori, and distinct taxonomic shifts characterized by decreased relative abundance of Firmicutes and Bacteroidota and increased Proteobacteria and Campylobacterota. Beta diversity analysis revealed significant clustering between H. pylori-positive and -negative groups (p < 0.001). No differences in microbiota composition were associated with age, pubertal stage, or gender. Histological gastritis severity correlated with specific microbiota alterations, and the presence of H. pylori and three co-occurring marker species distinguished severe gastritis profiles. The virulence factor CagA was associated with microbiota differences but not with histological severity.
INTRODUCTION: Chronic Helicobacter pylori (H. pylori) infection is a key risk factor for peptic ulcer disease (PUD) and gastric cancer in adults. However, current pediatric guidelines do not recommend eradication treatment in symptomatic children and adolescents without PUD lesions. The impact of H. pylori on the gastric microbiota in this population remains unclear.
METHODS: We conducted a prospective, multicenter study analyzing the gastric microbiota of 120 symptomatic patients aged 8-20 years undergoing endoscopy, including 41 H. pylori-positive and 79 H. pylori-negative individuals. Gastric mucosal samples were analyzed by 16S rRNA gene sequencing. Histological gastritis severity and H. pylori virulence factors were also assessed.
RESULTS: H. pylori-positive patients exhibited a significant reduction in microbial diversity, a higher dominance index primarily due to H. pylori, and distinct taxonomic shifts characterized by decreased relative abundance of Firmicutes and Bacteroidota and increased Proteobacteria and Campylobacterota. Beta diversity analysis revealed significant clustering between H. pylori-positive and -negative groups (p < 0.001). No differences in microbiota composition were associated with age, pubertal stage, or gender. Histological gastritis severity correlated with specific microbiota alterations, and the presence of H. pylori and three co-occurring marker species distinguished severe gastritis profiles. The virulence factor CagA was associated with microbiota differences but not with histological severity.
DISCUSSION: H. pylori infection in symptomatic children and adolescents without PUD is associated with profound gastric dysbiosis, independent of age or pubertal status. These findings support reconsidering earlier eradication strategies to prevent persistent gastric dysbiosis and potentially reduce long-term gastric disease risk.