Efficacy and safety of low-dose tetracycline, amoxicillin quadruple therapy in Helicobacter pylori infection: A retrospective single center study

Background: Helicobacter pylori (H. pylori) eradication rates have declined with the rise of antibiotic-resistant strains in recent years. Although highly effective with a low prevalence of resistance, standard dose tetracycline is associated with frequent adverse events. The efficacy and safety of low-dose tetracycline as part of tetracycline and amoxicillin-containing bismuth quadruple therapy are not well described. Aim: To compare the efficacy and safety of low-dose compared to standard dose tetracycline with combined amoxicillin-containing bismuth quadruple therapy in patients with H. pylori infection. Methods: Consecutive patients with H. pylori infection receiving tetracycline, amoxicillin, proton pump inhibitor, and bismuth for 14 days at Sir Run Run Shaw Hospital (1/2022-6/2023) were evaluated. The low-dose tetracycline group received tetracycline 500 mg twice daily (bid) while the standard dose group received 750 mg bid or 500 mg three times daily (tid). Primary endpoints were H. pylori eradication rate and treatment-related adverse events. Results: The mean age of the 218 patients was 48.7 +/- 14.0 years, 120 (55%) were male, and 118 (54.1%) received treatment as primary therapy. Furthermore, 73 (33%) patients received low-dose tetracycline (500 mg bid) and 145 (67%) received standard dose tetracycline including 500 mg tid in 74 (33%) and 750 mg bid in 71 (33%). On intention-to-treat analysis, H. pylori eradication rates were 89% [95% confidence interval (CI): 82%-96%] in the 500 mg bid group, 82% (95%CI: 74%-91%) in the 500 mg tid group, and 79% (95%CI: 69%-89%) in the 750 mg bid group without a statistically significant difference (P = 0.25). The incidence of adverse events was lower in the low-dose compared to the standard dose group (12.3% vs 31.1% or 23.9%; P = 0.02). Conclusion: Low-dose tetracycline combined with amoxicillin quadruple therapy for 14 days achieved a high eradication rate and fewer adverse events compared to the standard dose tetracycline regimen in patients with H. pylori infection.