About 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.
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).
Illnesses H.
pylori cause
Most people 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.
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.
H. pylori
infection diagnosis
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 for H. plyori:
-
Serological
tests (e.g. Clearview H. pylori
test) 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.
Eradication of
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 has 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.
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
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.
Infection and
prevention of 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.
Useful
links:
Center for Disease Control
and Prevention
National Institute of Diabetes &
Digestive & Kidney Diseases
www.cdc.gov/ulcer
www.familydoctor.org/