14-day Susceptibility-guided Bismuth Quadruple Therapy for Multiple Drug Resistant H. Pylori Infection

The goal of this clinical trial is to learn if the 14-day susceptibility-guided bismuth quadruple therapy works to treat multiple drug resistant Helicobacter pylori (H. pylori) in adults. It will also learn about the adverse effects of bismuth quadruple therapy. The main questions it aims to answer are:

* Does 14-day susceptibility-guided bismuth quadruple therapy higher the eradication rate?
* What medical problems do participants have when taking 14-day susceptibility-guided bismuth quadruple? Researchers will record 14-day susceptibility-guided bismuth quadruple to see if 14-day susceptibility-guided bismuth quadruple works to treat multiple drug resistant H. pylori.

Participants will:

* Take susceptibility-guided bismuth quadruple every day for 14 days
* Visit the clinic once 4-6 weeks for checkups and tests
* Keep a diary of their symptoms during taking susceptibility-guided bismuth quadruple

Helicobacter pylori (H. pylori) infection is the major culprit of dyspeptic symptoms, peptic ulcer disease, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma.

The antibiotic resistance of H. pylori infection is an emerging issue. Moreover, amoxicillin-resistant H. pylori strains increased recently. The amoxicillin resistance rates were 9% in Asia and up to 39% in South America.

Susceptibility-guided therapy is superior to empiric therapy in 2nd-line therapy. After twice eradication failure, H. pylori culture for susceptibility test is strongly recommended, which guide clinician to choose appropriate susceptibility-based therapy. The multiple drug resistant rates may be higher in patients who fail two or more eradication therapy; thus, susceptibility-guided therapy is currently the consensus recommendation for 3rd-line H. pylori eradication. Bismuth quadruple therapy could overcome either clarithromycin or metronidazole resistant strains. Several evidences of clinical randomized-controlled trials demonstrated that adding bismuth as the first line therapeutic regimen can capture additional 30%-40% successful eradication rate for the resistant strain, further contributing to the overall eradication rate.

Accordingly, the aim of our study was to validate the susceptibility-guided bismuth quadruple therapy in patients with multiple drug resistant H. pylori infection in terms of efficacy and side effects.

Eligibility Criteria:
Inclusion Criteria:

* H. pylori-infected with treatment experience with at least one course of eradication failure
* H. pylori-infected with treatment naïve but having multiple-drug resistant H. pylori (\>= three antibiotics)
* H. pylori infection confirmed by H. pylori culture

Exclusion Criteria:

* Previous allergic reactions to regimens, including amoxicillin, bismuth subcitrate, esomeprazole, metronidazole, rifabutin, and tetracycline,
* Severe comorbidities,
* Chronic kidney disease with estimated glomerular filtration rate \< 60 ml/min/1.73 m2,
* Pregnant or breastfeeding women.
* Dual-resistant H. pylori infection
* Mono-resistant H. pylori infection
* All susceptible H. pylori infection
* Positive RUT but negative H. pylori culture
* Negative RUT and negative H. pylori culture
* Decline to participate