About H.pylori
What is H. pylori?
Helicobacter pylori (H.pylori) is a gram
negative, multiflagellate, microaerophilic, spiral shaped
bacterium. It is found in the stomach, deep in gastric pits,
adhering to the surface of epithelial cells mainly beneath the
protective gastric mucus layer. In this environment, H
pylori is able to thrive free from the competition of other
micro-organisms.
Before 1983,when this bacterium was first confirmed to be
associated with peptic ulcers, it was thought that they were caused
by stress, spicy food and general lifestyle. At this time, the
majority of patients with peptic ulcers were treated with long-term
maintenance doses of acid-reducing medication, such as H2 blockers.
Since the discovery of the link between the organism and ulcers it
has now been found that H.pylori causes more than 90% of
duodenal ulcers and 80% of gastric ulcers.
With this knowledge, appropriate antibiotic regimens can
successfully eradicate H.pylori in most patients, with
complete resolution of the mucosal inflammation and a minimal
chance of ulcer recurrence.
How common is H. pylori Infection?
Over 50% of the world’s population is infected with
H.pylori, but in some less developed countries it maybe as
high as 80-90%. In the Western world (e.g. USA), H.pylori
is more prevalent among older adults (50 years +), with a
predomination in groups such as black and Hispanic Americans and
those in the lower socioeconomic groups. In other regions the age
related prevalence differs and is extremely common in childhood in
certain countries (e.g. China).
What illnesses does H.pylori
cause?
Most persons infected with H.pylori never suffer any
symptoms related to the infection, but once someone is infected the
organism (if left untreated), can live indefinitely in the stomach
and may not cause any clinical illness until many years later.
H.pylori can cause chronic active, chronic persistent and
atrophic gastritis in adults and children plus it causes duodenal
and gastric ulcers. It does this
as H.pylori weakens the protective mucus coating
of the stomach and duodenum allowing gastric acid to get through to
the sensitive lining beneath.
Infected persons with H.pylori have a 2 to 6 fold
increased risk of developing gastric cancer and
mucosal-associated-lymphoid-type (MALT) lymphoma as compared to
uninfected persons.
What are the symptoms of an ulcer?
Abdominal discomfort is the most common ulcer symptom and is
usually characterised by a gnawing or burning pain in the
epigastrum. This pain typically occurs when the stomach is empty,
occurring 2-3 hours after a meal or in the early morning hours. It
may last for a matter of minutes or for hours and may be relieved
by food or antacid medications. Other less common symptoms include
nausea, poor appetite, vomiting, bloating and burping.
It is important to contact a doctor immediately if any of the
following systems are experienced: - sharp, sudden persistent
stomach pain, black/bloody stools or bloody vomit as these could be
signs of a more serious problem such as ulcer perforation, bleeding
or obstruction.
How is H.pylori infection
diagnosed?
There is a number of methods that can be used to diagnose
H.pylori infection but they basically fall into two main
categories- Invasive and Non-Invasive.
Invasive Tests
Invasive tests require a gastric biopsy sample and there are
three major methods of detecting H.pylori in this
category.
Culture - requires an experienced laboratory but allows precise
identification and is necessary when antimicrobial susceptibility
testing is desired. Nb. Cultures are typically incubated in
microaerobic conditions for up to 10 days.
Histology - histological identification of organism is
considered by many to be the gold standard of diagnostic tests but
results are dependent upon the skill and experience of the observer
and results maybe difficult to interpret if only a few organisms
are present.
Rapid Urease test (CLO Test) - a biopsy sample is incubated on
an agar based medium containing urea. If H.pylori is
present in the sample, the bacterial urease converts urea to
ammonia and a colour change indicator detects the subsequent pH
rise in the medium. The test takes a minimum of one hour but its
sensitivity is increased by longer incubation periods.
Non-Invasive Tests
Typically there are two types of non-invasive diagnostic tests:
-
- Serological tests (e.g. Clearview H.pylori) that
detect specific antibodies in response to the H.pylori
infection with blood or serum being the most common samples used.
The sensitivity and specificity of these assays ranges between
80-95% dependent on the assay.
- Urea Breath Test- In this test the patient is given either a
C13 or C14 labelled urea to drink. If H.pylori is present
it metabolises the urea rapidly and labelled carbon dioxide is
expired in the patients breath. The labelled carbon dioxide is
measured by mass spectrometry or scintillation counting
respectively.
Why eradicate H.pylori in patients with peptic
ulcers?
H.pylori should be eradicated in all H.pylori
related ulcers whether it is active or not for the following
reasons: -
- It prevents relapses- Treatment ahs been found to reduce the
relapse rate from 80% to less than 5%.
- It prevents ulcers re-bleeding.
- It’s more cost effective than anti-secretory therapy as it
fewer endoscopies are needed, there are fewer clinic visits, there
are lower drug costs and it results in less work days lost.
What are the treatment regimens for the eradication of
H.pylori?
H.pylori related peptic ulcer treatment usually
consists of a combination drug therapy that kill the bacteria,
reduces stomach acid and protects the stomach lining. Drugs used in
the combination therapy are as follows: -
- Antibiotics- Metronidazole, Tetracycline, Clarithromycin &
Amoxicillin
- Acid Suppressing drugs
- H2 blockers-Cimetidine, Rantidine, Famotidine &
Nizatidine
- Proton Pump Inhibitors (PPI)-Omeprazole, Lansprazole &
Rabeprazole
- Stomach lining shield - Bismuth subsalicylate.
It is not recommended to treat H.pylori with a single
medication so combination therapy should always be used. There are
a number of combination therapies in common use e.g. dual, triple
and quadruple, but at this time the most proven effective treatment
is a 2-week course of triple therapy. This involves taking two
antibiotics to kill the bacteria and either an acid suppressor or
stomach-lining shield. This therapy regimen reduces ulcer symptoms,
kills the bacteria and prevents recurrence in more than 90% of
patients.
What are the long-term consequences of H.pylori
infection?
A number of studies have shown that there is a strong
association between long-term H.pylori infection and the
development of gastric cancer. Gastric cancer is the second most
common cancer worldwide and it is most common in countries such as
China and Colombia where there is an extremely high infection rate
with H.pylori.
How do people become infected and what can be done to
prevent H.pylori infection?
It is not know exactly how H.pylori is transmitted or
why some people become symptomatic while others do not. The most
likely way of spreading the bacterium is from person to person via
faecal-oral or oral-oral routes. It is also possible that the
organism is spread through contaminated water. There are also
documented cases of bacterial spread through the use of improperly
cleaned and sterilised medical equipment such as endoscopes.
As the precise routes of transmission are unknown it is
difficult to make any recommendations on how to reduce the spread
of infection but in general as with many other infections, it is
advisable to wash hands thoroughly, to eat food that has been
properly prepared and drink water from a known clean source.
Some key economic facts about the peptic ulcers and
H.pylori infection:
(From the USA as most studies on the economic impact have been
conducted there)
- Ulcers cause an estimated 1 million hospitalisation and 6500
deaths per annum.
- The annual health care costs of peptic ulcer have been
estimated to $6 billion.
- Studies indicate that curing an ulcer with antibiotics/triple
therapy takes less time and cost one tenth of the amount of
treating ulcer symptoms over a lifetime.
- Acid-reducing maintenance therapy over 15-year period is
estimated to cost $11,000. Compared to antibiotic therapy, which
takes place over 14-21 days and costs less than a $1,000 over the
same period.