Protocol for a randomised 'screen-and-treat' Helicobacter pylori eradication trial in 14-18-years-old adolescents residing in three regions of Chile: effectiveness and microbiological host implications

Abstract

Introduction: Gastric cancer is a major global health concern, being the final stage of a long-term process, primarily associated with Helicobacter pylori (H. pylori) infection. Early childhood acquisition of H. pylori with low spontaneous eradication rates underscores the need for preventive measures. Our previous pilot treatment study revealed high eradication rates, favourable tolerance profile and a decline in serum biomarkers indicative of gastric damage in asymptomatic school-aged children. The purpose of this study is to determine the potential benefit of a 'screen-and-treat' strategy targeting persistently infected, asymptomatic adolescents. Specific aims are to assess eradication efficacy, its clinical and molecular outcomes and potential clinical and microbiological side effects.

Methods and analysis: The screening phase will involve testing 500-1000 asymptomatic adolescents aged 14-18 from three cities in Chile using the urea breath test (UBT) to identify 210 participants with persistent infection. They will proceed to a randomised, non-blinded, controlled trial, receiving either a sequential eradication scheme for H. pylori or no treatment. Follow-up will span up to 24 months post-treatment, involving UBT, gastroenterological assessments and blood and stool sample collections. Concurrently, a subset of 60 uninfected adolescents will undergo matched follow-up. Enzyme-linked immunosorbent assay (ELISA) commercial kits will evaluate gastric damage biomarkers in serum (pepsinogen I and II, gastrin-17, VCAM-1, CXCL13). Stool samples will be employed for Escherichia coli and Enterococcus spp-culture, assessing AMR via the disk diffusion method. H. pylori clarithromycin resistance will be determined by molecular method from stool samples. The gut microbiome will be characterised by amplifying and sequencing the 16S rRNA gene from stool samples, followed by bioinformatics analysis.

Ethics and dissemination: Approved by the Human Research Ethics Committee at the Faculty of Medicine, University of Chile (073-2022). Findings will be disseminated in peer-reviewed journals and scientific meetings to guide future practices.

Trial registration number: NCT05926804.

Keywords: Adolescents; Clinical Trial; Paediatric infectious disease and immunisation.

Figure 1. Flowchart: trial phases and activities. H. pylori, Helicobacter pylori; UBT, urea breath test.