Associations have been made between Helicobacter pylori and:

• peptic ulcers - the majority of gastric antrum is colonised in ulcer patients
• duodenal ulcer - gastric metaplasia, able to colonise, followed by duodenitis
• gastric ulcer - acid hypersecretion
• acute and chronic gastritis - type B strain
• gastric associated lymphoid tumours

The relapse rate for duodenal ulcers is:

• 20% when H. pylori is eradicated
• 80% when it is not