Molecular Detection of Multiple Antimicrobial Resistance Genes in Helicobacter pylori-Positive Gastric Samples from Patients Undergoing Upper Gastrointestinal Endoscopy with Gastric Biopsy in Algarve, Portugal

<b>Background/Objectives</b>: <i>Helicobacter pylori</i> (<i>H. pylori</i>) is a common gastric pathogen linked to gastritis, gastroduodenal ulcers, and gastric cancer. Rising antimicrobial resistance (AMR) poses challenges for effective treatment and has prompted the WHO to classify <i>H. pylori</i> as a high-priority pathogen. This study aimed to detect the prevalence of AMR genes in <i>H. pylori</i>-positive gastric samples from patients in Algarve, Portugal, where regional data is scarce. <b>Methods</b>: Eighteen <i>H. pylori</i>-positive gastric biopsy samples from patients undergoing upper gastrointestinal endoscopy were analyzed. PCR and sequencing were used to identify genes associated with resistance to amoxicillin (<i>Pbp1A</i>), metronidazole (<i>rdxA</i>, <i>frxA</i>), tetracycline (<i>16S rRNA</i> mutation) and clarithromycin (<i>23S rRNA</i>). Sequence identity and homologies were verified using tBLASTx and the Comprehensive Antibiotic Resistance Database (CARD). <b>Results:</b> Out of the 18 <i>H. pylori</i>-positive samples, 16 (88.9%) contained at least one AMR gene. The most frequent genes were <i>rdxA</i> (83.3%) and <i>frxA</i> (66.7%) for metronidazole resistance, and the <i>16S rRNA</i> mutation (66.7%) for tetracycline. Resistance to amoxicillin and clarithromycin was detected in 27.8% and 16.7% of cases, respectively. Most samples (72.2%) had multiple resistance genes. A significantly strong association was found between female sex and the presence of the <i>rdxA</i> gene (<i>p</i> = 0.043). <b>Conclusions</b>: The study reveals a high prevalence of <i>H. pylori</i> resistance genes in Algarve, particularly against metronidazole and tetracycline. These findings highlight the need for local surveillance and tailored treatment strategies. Further research with larger populations is warranted to assess regional resistance patterns and improve eradication efforts.