Update on the second-line treatment of infection: a narrative review.

A standard bismuth quadruple therapy, a fluoroquinolone-containing triple (or quadruple) therapy or a proton pump inhibitor (PPI)-amoxicillin high-dose dual therapy has been recommended as a second-line treatment for infection by the Maastricht VI/Florence Consensus Report. The major shortcoming of levofloxacin-amoxicillin triple therapy is low cure rate for eradicating levofloxacin-resistant strains. With the rising prevalence of levofloxacin-resistant strains, levofloxacin-amoxicillin triple therapy cannot reliably achieve a high eradication rate for second-line treatment of infection in most countries now. The present article aims to review current second-line eradication regimens with a per-protocol eradication rate exceeding 85% in most geographic areas. Recently, a novel tetracycline-levofloxacin quadruple therapy consisting of a PPI, bismuth, tetracycline, and levofloxacin for rescue treatment of infection has been developed. The new therapy achieved a higher per-protocol eradication rate than levofloxacin-amoxicillin triple treatment in a randomized controlled trial (98% 69%). Additionally, the tetracycline-levofloxacin quadruple therapy also exhibits a higher eradication rate than amoxicillin-levofloxacin quadruple therapy. High-dose dual PPI-amoxicillin therapy is another novel second-line treatment for infection. The new therapy can achieve an eradication rate of 89% by per-protocol analysis for the second-line treatment in Taiwan. Recently, levofloxacin-based sequential quadruple therapy and potassium-competitive acid blocker have also been applied in the second-line treatment of infection. A meta-analysis revealed that a vonoprazan-based regimen has significant superiority over a PPI-based regimen for second-line eradication therapy. In conclusion, the eradication rate of levofloxacin-amoxicillin triple therapy is suboptimal in the second-line treatment of infection now. Currently, a standard bismuth quadruple therapy (tetracycline-metronidazole quadruple therapy), a tetracycline-levofloxacin quadruple therapy, an amoxicillin-levofloxacin quadruple therapy, a levofloxacin-based sequential quadruple therapy or a high-dose PPI-amoxicillin dual therapy is recommended for the second-line treatment of infection.