Author: Dr Shamsul Islam, MBBS, FRACP, PhD. Consultant Gastroenterologist, QE-II Jubilee Hospital, Brisbane, Senior Lecturer, University of Queensland.
Helicobacter pylori (HP) is an important upper gastrointestinal pathogen in humans.
It is an ancient infection detected even in the Egyptian mummies.
HP is known to be positively associated with human diseases since the pioneering work of the Australian duo Warren and Marshall in Perth in the 1970s and 80s who were subsequently awarded the Nobel Prize for Medicine in 2005.
HP is a comma shaped ubiquitous bacteria mostly found in human stomach lining being more prevalent in the East than in the West, the respective prevalence rates of infection being 80 - 90 per cent and 40 - 50 per cent giving a rough global prevalence of about 50 per cent.

The route of transmission of the bacteria from human to human is thought to be via oro-oral or faeco-oral routes in early part of life and its prevalence increases with age.
Not all persons infected will be ill but symptoms such as nausea, vomiting, abdominal pains, bloating, belching (non-ulcer dyspepsia) are present in symptomatic individuals. Duodenal and gastric ulcers are associated with chronic HP infection in 80 - 90 per cent and 50 - 60 per cent respectively.
Other pathologies associated with HP are: acute and chronic gastritis, atrophic gastritis, MALT lymphoma (Mucosal Associated Lymphoid Tissue lymphoma), stomach cancer via gastric atrophy, iron deficiency, ITP (idiopathic thrombocytopaenic purpura), etc.

The diagnosis is made with serology, urea breath test (UBT), stool antigen test and histology and urease test on endoscopically obtained gastric biopsy samples.
Rarely culture of the biopsy samples would be used for sensitivity studies when initial attempts to eradicate the infection fail, especially after repeated treatment failures.
The World Health Organisation (WHO) declared it as a class one human carcinogen hence most authorities would recommend eradication therapy in adults unless contra-indicated.
Definite indications for treatment include: peptic ulcer (past or present), chronic atrophic HP gastritis, MALT lymphoma and infected individuals with family history of gastric cancer.

Young children, individuals with multiple antibiotics allergy, pregnant women are those in whom treatment guidelines are not clear.
Initial treatment would consist of two-three antibiotics along with a proton pump inhibitor (PPI) given over one-two weeks period.
Most regimes would cure the infection in 80 - 85 per cent of cases while the recrudescence rate is about one-two per cent per year.
In low endemic areas, the treatment is usually simple consisting of two antibiotics (e.g. Amoxycillin plus Clarithromycin) and a PPI given over a one week period which gives a cute rate of 80 - 85 per cent.
However, in areas where resistance to the antibiotics used is high (e.g. >15 - 20 per cent), three different antibiotic drugs plus a PPI may be required for two weeks.
There is now a world-wide trend for sequential treatment or use a two weeks treatment for all to start with.
In rare cases a two week rescue therapy with three antibiotics regimen based on Rifampicin may need to be used.
The cure rate would depend on the local antibiotics resistance pattern to HP. Common antibiotics/antimicrobials used in the regimes are: Amoxycillin, Clarithromycin, Metronidazole, Tetracycline, and Bismuth while second and third-line agents would include - Ciprofloxacin, Moxifloxacin, Azithromycin and Rifabutin.
There is a world-wide trend towards increasing resistance to Metronidazole and Clarithromycin.

Confirmation of eradication is performed by UBT, (considered “gold-standard”) four - 12 weeks after the end of treatment course.
Stool antigen testing is also useful while serology is slow to become negative rendering it unhelpful.
It can also be done by gastroscopic examination of the stomach with histology or urease tests performed on the gastric mucosal tissue samples especially when the procedure is performed for additional indications.
Treatment failure may be as high as 20 per cent when second or third line therapies could be of particular use.
Several factors may reduce the sensitivity of detection of HP (false-negative) like recent use of antibiotics, PPI or Bismuth containing drugs hence they should be excluded for about two weeks before testing.

The re-infection rate is higher in endemic areas so it would be logical to test and treat periodically to reduce morbidities.
Due to systematic treatment of the HP infection, the natural history of peptic ulcer disease has significantly changed world-wide.