Evolution and Detection of β-Lactamases in Helicobacter pylori Isolates from High- and Low-Risk Southwestern Colombian Areas for Gastric Cancer

Gastric cancer (GC) is one of the leading causes of cancer-related mortality worldwide, with Helicobacter pylori infection recognized as its main risk factor. Eradication therapy is the cornerstone of GC prevention; however, increasing antimicrobial resistance (AMR) threatens the effectiveness of amoxicillin-based regimens. This study investigated the occurrence and evolutionary distribution of β-lactamase genes in Colombian H. pylori isolates. A total of 67 H. pylori isolates from Colombian regions with high and low GC risk were analyzed. The presence of blaTEM and blaSHV genes was assessed using PCR, following in silico primer validation against complete H. pylori genomes. Phylogenomic relationships were reconstructed using the Neighbor-Joining method in MEGA XI, with the best-fitting evolutionary model selected according to (AIC). The GTR + G + I model was identified as the optimal model and was subsequently used for phylogenetic reconstruction. The resulting tree was visualized using iTOL. This study reports, for the first time in Colombia, that the presence of β-lactamase genes in H. pylori. blaTEM and blaSHV were detected in 9 of 48 Andean isolates (18.75%), whereas no β-lactamase genes were identified in isolates from the low-risk Pacific region. These genes were associated with genetic potential for amoxicillin resistance. Phylogenomic analysis identified a distinct Andean lineage in which all β-lactamase-positive isolates clustered. β-Lactamase genes in Colombian H. pylori are geographically restricted to high-risk Andean populations and associated with a defined phylogenetic lineage. These findings provide new insights into the evolution of amoxicillin resistance and support the implementation of genomic surveillance to optimize eradication strategies and improve precision management of H. pylori infection.