RT Journal Article T1 Gastric microbiota-specific signatures in adults with obesity and Helicobacter pylori-negative gastritis A1 Martínez-Montoro, José Ignacio A1 Sancho-Marín, Raquel A1 Ocaña-Wilhelmi, Luis Tomás A1 Arranz-Salas, Isabel A1 Ruiz-Campos, Nerea A1 García-López, María José A1 Tinahones-Madueño, Francisco José A1 Gutiérrez-Repiso, Carolina K1 Estómago - Enfermedades K1 Enfermedades crónicas K1 Obesidad AB Background The role of the gastric microbiome in the pathophysiology of gastritis beyond Helicobacter pylori (HP) infection is poorly understood and has remained unexplored in patients with obesity. The aim of this study was to analyse gastric mucosa-associated microbiota in patients with obesity and nonatrophic chronic gastritis in the absence of HP infection or history of HP eradication. Methods This was a case–control study conducted at Virgen de la Victoria University Hospital in Malaga, performed in patients with severe obesity (body mass index ≥40 kg/m2) undergoing sleeve gastrectomy, without HP infection and no history of HP eradication. Gastric biopsy specimens were collected at surgery and were analysed by 16S rRNA sequencing. Participants were divided into two groups according to the histological evaluation: nonatrophic chronic gastritis and nongastritis. An exploratory prospective analysis to determine the influence of gastritis on short-term outcomes after surgery was also performed. Results Sixty-seven participants (38 in the gastritis and 29 in the nongastritis group) were included. A lower alpha diversity (evenness and Shannon diversity indexes) and beta diversity (weighted Unifrac distance) were shown in the gastritis group. Higher relative abundances in the families Micrococcaceae, Streptococcaceae and Leuconostocaceae and the genera Streptococcus, Weissella and Cryptobacterium were observed in the gastritis group, compared with the nongastritis group. An enrichment in pathways involved in toluene degradation, heterolactic fermentation and secondary metabolites biosynthesis, such as ergothioneine and terpenoids, was found in the gastritis group. Also, higher total cholesterol levels 1 year after the surgery were observed in the gastritis group compared with the nongastritis group, although no within-group differences from baseline to 1 year were detected in this parameter. PB Wiley SN 0014-2972 YR 2025 FD 2025-06-07 LK https://hdl.handle.net/10630/39026 UL https://hdl.handle.net/10630/39026 LA eng NO Martínez-Montoro, J. I., Sancho-Marín, R., Ocaña-Wilhelmi, L., Arranz-Salas, I., Ruiz-Campos, N., García-López, M. J., Tinahones, F. J., & Gutiérrez-Repiso, C. (2025). Gastric microbiota-specific signatures in adults with obesity and Helicobacter pylori-negative gastritis. European Journal of Clinical Investigation, n/a(n/a), e70085. NO Funding for open access charge: Universidad de Málaga / CBUA DS RIUMA. Repositorio Institucional de la Universidad de Málaga RD 24 ene 2026