Helicobacter pylori

Overview

•Gram-negative, microaerophilic, spiral bacillus - survives gastric acid via urease (converts urea → ammonia + CO₂, locally neutralising pH)

•Present in ~95% of duodenal ulcers and 70-80% of gastric ulcers

•WHO Group 1 carcinogen - drives Correa cascade (chronic gastritis → atrophy → intestinal metaplasia → dysplasia → adenocarcinoma)

Presentation

•Most infections are asymptomatic; symptoms reflect gastritis/peptic ulceration

•Epigastric pain - burning/gnawing; relieved by food (duodenal ulcer) or worsened by food (gastric ulcer)

•Bloating, nausea, early satiety

•Alarm features - require urgent OGD (do NOT use test-and-treat):

•Unintentional weight loss, dysphagia/odynophagia, persistent vomiting, iron-deficiency anaemia, epigastric mass, age >55 with new-onset unexplained dyspepsia

Investigations

⚠️
Stop PPIs at least 2 weeks and antibiotics at least 4 weeks before any active H. pylori test (UBT, SAT, CLO). Failure to do so causes false-negative results. Serology is unaffected - but cannot confirm eradication.

H. pylori diagnostic tests
TestSettingKey points
Carbon-13 urea breath test (UBT)Non-invasive (primary care)Preferred for diagnosis and confirmation of eradication; highly sensitive and specific
Stool antigen test (SAT)Non-invasive (primary care)Convenient alternative to UBT; good sensitivity/specificity
Rapid urease test (CLO test)Endoscopy onlyBiopsy in urea medium; colour change if urease present; result in minutes-hours
HistologyEndoscopy onlyDirect visualisation of organisms + mucosal changes (gastritis, metaplasia, dysplasia)
Serology (IgG)Non-invasiveNot recommended for test-of-cure - antibodies persist up to 12 months post-eradication

Test	Setting	Key points
Carbon-13 urea breath test (UBT)	Non-invasive (primary care)	Preferred for diagnosis and confirmation of eradication; highly sensitive and specific
Stool antigen test (SAT)	Non-invasive (primary care)	Convenient alternative to UBT; good sensitivity/specificity
Rapid urease test (CLO test)	Endoscopy only	Biopsy in urea medium; colour change if urease present; result in minutes-hours
Histology	Endoscopy only	Direct visualisation of organisms + mucosal changes (gastritis, metaplasia, dysplasia)
Serology (IgG)	Non-invasive	Not recommended for test-of-cure - antibodies persist up to 12 months post-eradication

Management

🥇 First-line

•7-day triple therapy - omeprazole (or any PPI) 20 mg + amoxicillin 1 g + clarithromycin 500 mg, all twice daily

•Penicillin allergy: replace amoxicillin with metronidazole 400 mg twice daily

🥈 Second-line

•Repeat 7-day triple therapy using the antibiotic NOT previously given - PPI + amoxicillin + metronidazole (if clarithromycin used first) or PPI + amoxicillin + clarithromycin (if metronidazole used first)

🥉 Third-line

•7-day quadruple/rescue therapy - PPI + amoxicillin + tetracycline (or quinolone); refer to gastroenterology for culture-guided sensitivity testing

🎯
Confirm eradication with UBT or SAT at 4-8 weeks after completing treatment. Do not retest earlier - residual antibiotic activity can suppress bacteria without eradicating them, causing a false-negative. Routine confirmatory retest is recommended in peptic ulcer disease; in dyspepsia, only if symptoms return.

Complications

•Peptic ulcer disease - eradication dramatically reduces recurrence

•Gastric adenocarcinoma - via Correa cascade; WHO Group 1 carcinogen

•Gastric MALT lymphoma - H. pylori eradication alone can induce remission in stage I low-grade MALT lymphoma

•Upper GI haemorrhage - haematemesis or melaena from peptic ulceration

•Perforation - surgical emergency; sudden severe epigastric pain + peritonism

•Gastric outlet obstruction - pyloric scarring; projectile vomiting of undigested food