Abstract: Objective To establish a multiplex PCR-based method for detecting Helicobacter pylori (Hp) 16S rRNA gene and cagA gene in saliva samples for investigating the prevalence of Hp in the oral cavity of Hp-infected patients with digestive tract diseases. Methods Bioinformatics technique was used to design specific primers for Hp 16S rRNA and cagA genes for Hp detection using multiplex PCR, with recombinant cloning plasmids serving as the standard positive control. Oral saliva samples were collected from 156 patients with digestive tract diseases, and Hp 16S rRNA and cagA genes were detected using the established multiplex PCR system. Results The established multiplex PCR system showed a strong specificity and a high sensitivity for detecting Hp 16S rRNA gene and cagA gene, with the lowest detection limit of 103 copies/μL. The recombinant plasmids pGMT-16s and pGMT-cagA could be used as standard positive controls for the identification of Hp. Among the 156 saliva samples, 87.2% were positive for Hp 16S rRNA gene and 23.1% for Hp cagA gene. Conclusion Hp is highly prevalent in saliva specimens of Hp-infected patients with digestive tract diseases. The presence of Hp in the oral cavity may importantly contribute to Hp infection in the digestive tract and recurrence after treatment.

Key words: Helicobacter pylori; 16S rRNA gene; cagA gene; saliva