Gastric cancer is one of the leading causes of cancer-related deaths worldwide. In Taiwan, there are around 3800 fresh cases annually, with about 5% of total cancers cases. Gastric cancer development is known to follow a multistate process from non-atrophic gastritis, atrophic gastritis, intestinal metaplasia, dysplasia, and carcinoma; H. pylori infection plays the key role of this carcinogenic process. Although H. pylori eradication would result in a marked gastric cancer reduction, treatment success using standard regimens has become more difficult in recent years, and increased antibiotic resistance is considered the most important reason for decreased treatment efficacy. As no specific new medications have been introduced in recent years, novel treatment regimens have been created using different combinations, durations and sequences of available medications. The addition of bismuth improved the cure rates despite a high prevalence of resistance, and resistance of H. pylori to bismuth has not been reported. Bismuth absorption is not required for efficacy in H. pylori treatment regimens, suggesting a local mechanism of action. The mechanisms of bismuth with responsible for rapid destruction of H. pylori within the stomach remain unclear. Knowledge of the mechanism of action of bismuth compounds against H. pylori would be beneficial in the development of improved treatment regimens in this era of declining eradication success rates. We conduct the pilot study to evaluate the bacteria fragments of H. pylori in specimen through electron microscopy after bismuth therapy and provide insight into the mechanism of action of pH on bismuth therapy. We also help to develop optimal H. pylori therapeutic strategies.

Inclusion criteria

1. Age 20-69
2. Confirmed H. pylori infection by urea breath test or previous histology
3. Scheduled endoscopy
4. Mentally competent to be able to understand the consent form for individuals equal to or older than 20
5. Able to communicate with study staff for individuals equal to or older than 20
6. Without history of gastric cancer Exclusion criteria

1.History of gastric cancer

Deferral criteria:

1. Having received antibiotic treatment in the previous 15 days
2. Need of time to decide participation