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Background: Helicobacter pylori (H pylori) is responsible for various diseases including cancer It co‐evolved with humans, and human migrations shaped the expansion and the diversity of strains around the world. The risk of developing a disease depends on virulence factors, mainly the cytotoxin‐associated gene A protein (CagA). The aim of this study was to determine the cagA status in H pylori strains from Mauritanian patients and to search for a relationship with endoscopic and histologic findings. Material and methods: H pylori was searched in gastric biopsies taken during endoscopy in patients with gastro‐duodenal symptoms. RT‐PCR was used for the diagnosis and resistance to clarithromycin. The cagA status was determined with PCR and the EPIYA‐cagA polymorphism with sequencing. Results: At all, 76/78 (97.4%) biopsies were positive. The rate of clarithromycin resistance was 4/76 (5.26%) due to the A2143G mutation, with a mixed population in 2 cases. The cagA gene was present in 23/76 (30.26%) biopsies, and the EPIYA motif was ABC in 21 (91.3%). High bacterial load and inflammation were significantly associated with cagA‐positive status (P <.01). Phylogenetic analysis of the glmM and hspA genes highlighted a mixture of African and European genes in strains of H pylori isolated from patients of Moor origin. Conclusion: We report a high prevalence of H pylori infection in Mauritanian patients, a low rate of clarithromycin resistance (5.26%) and high bacterial load and inflammation associated with cagA‐positive status. The phylogenetic analysis highlights the mix of different populations leading to the Moor ethnicity. [ABSTRACT FROM AUTHOR]

Reliable diagnostic methods are mandatory for effective management of Helicobacter pylori infection. Histology and culture are the most common invasive methods in current practice, even if molecular methods are gaining in importance. The performance of these conventional methods varies significantly. We conducted a retrospective study of 1540 adults and 504 children with gastric biopsies taken during endoscopy to assess the impact of bacterial load and the cagA virulence factor on the performance of H. pylori infection testing. The association between virulence and histology findings was also investigated. With 23S rRNA qPCR confirmed by glmM amplification as the gold standard, culture and histology had lower sensitivity, 74.4% and 73.3%, respectively. However, their sensitivity was enhanced (>90%) in biopsies with high bacterial load (qPCR Ct < 30). Positive cagA status of the strain was associated with high bacterial load (94.9%), thus resulting in more frequent positive culture (94.3%) and H. pylori histology detection (91.7%) and more severe lesions on histology (p < 0.001). Conversely, the cagA status of the strains was negative in 110/119 (92.4%) of biopsies with low bacterial load (qPCR Ct < 30), 82/90 (91.1%) with negative H. pylori histology detection and 119/131 (90%) with negative culture findings (p < 0.001). This study highlights the low sensitivity of conventional culture and histology that may lead to false negative diagnosis if used alone. H. pylori quantification associated with cagA genotyping in routine workflow are essential for a sensitive and reliable diagnosis, to identify patients at high risk and to manage eradication therapies. [ABSTRACT FROM AUTHOR]