Helicobacter pylori infection is a widespread bacterial disease affecting nearly half of the world's population. In children, the infection displays distinct features versus adults, with lower prevalence, variable symptoms, and differing endoscopic and histological appearances.

Typically acquired in early childhood, its transmission is closely linked to socio-economic disadvantage and overcrowding. Although most infected children are asymptomatic, some develop epigastric pain, dyspepsia, weight loss, or other gastrointestinal disturbances. Chronic infection may eventually lead to mucosal atrophy and intestinal metaplasia, increasing the risk of gastric cancer later in life. Given the limitations and risks of invasive diagnostic methods-especially endoscopy under general anesthesia-there is a critical need for reliable, non-invasive tests. Recent adult studies indicate that stool-based PCR is a promising alternative for both detecting H. pylori and identifying clarithromycin resistance.

The primary objectives of this study are to evaluate the intrinsic diagnostic performance of high-resolution melt PCR (HP PCR) in stools, and to compare these results with those obtained from a conventional work-up, such as gastric biopsies, in a paediatric population. In accordance with prevailing rationality, the principal outcome of this study will be an evaluation of the intrinsic diagnostic capabilities of the proposed method. This will be accomplished by conducting a comparison of the sensitivity and specificity of the PCR test in stools with those of gastric biopsies (reference test).

Inclusion Criteria:

• Age < or = 16 years ;
• Any indication for gastroscopy in children requiring gastric biopsies: gastro-esophageal reflux resistant to proton pump inhibitors (PPIs) or recurrent on discontinuation of PPIs, hematemesis, refractory anemia or unexplained inflammatory syndrome, recurrent vomiting, dysphagia, endoscopic assessment of chronic inflammatory bowel disease with search for H. pylori superinfection ;
• Patients benefiting from a Social Security scheme or benefiting from one via a third part;
• Holders of parental authority who have given their informed consent to participate in the study and child participants of understanding age who have given their assent.

Non-inclusion Criteria:

• Antibiotic treatment less than 4 weeks
• PPIs treatment less than 2 weeks
• Contraindication to endoscopic procedure or biopsy.

Exclusion Criteria:

• Antibiotic therapy prior to stool collection (between inclusion and stool collection, which may be 10 days later)
• Failure to send/receive stool sample
• Biopsy not performed at endoscopy

Children requiring gastric biopsies for H. pylori detection