Twenty-five years ago, many people underwent major stomach surgery because of ulcers.  Medications such as cimetidine were then developed that controlled the problem effectively but required taking a drug that often affected a variety of body systems for long periods of time. Recently, bacterial infection with Helicobacter pylori (H. pylori) has become recognized as the main cause of ulcers. 

Not only is H.pylori infection the main cause of peptic ulcer disease and gastritis, it has also been associated with gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma.  The organism is found in 20-40% of Canadians and the prevalence increases with age.  The lifetime risk of peptic ulcers in adults with H.pylori is approximately twice as much as persons without H.pylori.

The Guidelines and Protocols Advisory Committee (BCMA and Ministry of Health) have published a document entitled “Clinical Approach to Adult Patients with Dyspepsia”  (www.healthservices.gov.bc.ca/msp).

This protocol suggests that patients with “alarm features” (such as bleeding) require prompt investigation with upper GI endoscopy and biopsy.  Those patients who do not present with “alarm symptoms” have two options. (1) They can be tested for H.pylori infection.  If the test is positive, then antibiotic eradication is required.  If the test is negative, empiric therapy consisting of a 4-week course of a histamine-2 receptor antagonist or a proton pump inhibitor is recommended. (2) Alternately, but more complicated, the empiric therapy can be used as the initial approach with UBT to follow when appropriate.

The assessment of successful treatment for H.pylori is performed using the Urea Breath Test, six-weeks after the course of antibiotic therapy. 

There are several tests for the diagnosis of H.pylori.

Serology:  Serological tests detect the presence of antibodies to H.pylori. Positive serology indicates current or past infection with H.pylori. A positive test does not confirm active disease.  A negative serological test provides >95 % assurance that there is no H.pylori infection. Serology should not be used in the evaluation of treatment of H.pylori because the antibody titre takes many months (or even years) to decline.

Urea Breath Test (UBT):  The patient is asked to drink a dilute solution containing labeled urea.  H.pylori contains urease, an enzyme that splits urea into CO2 and NH3.  The CO2 is then absorbed into the bloodstream and rapidly exhaled in the breath.  The presence of labeled CO2 in a breath sample has 98 % sensitivity and 99 % specificity for the presence of H.pylori.

Two labels have been employed. C-14 is a beta-emitting radioactive isotope with a half-life of over 5,000 years that is detected by beta-scintillation. C-13 is a non-radioactive, stable isotope that is measured by mass spectrometry.

Biopsy for culture and histology:  Biopsy is considered to be the gold standard.  However, it is invasive, expensive, and less sensitive (because of sampling errors and bacterial growth failures) than the UBT.

Other tests: Salivary antigen detection has been evaluated but found to have unacceptable accuracy for the diagnosis of H. pylori infection. A fecal antigen detection test has also been developed, but more experience with the test is needed to assess its clinical utility.

The best test:

The C-13 UBT has been recommended as a clinical gold standard against which other diagnostic methods can be validated. 

In children under two years of age, the UBT may be difficult to administer and borderline results are common. Persons with end-stage chronic obstructive pulmonary disease cannot produce adequately mixed breath samples and should not be tested.

To evaluate the successful eradication of H. pylori a UBT test is recommended six weeks after antibiotic therapy has terminated.  Undertaking the UBT prior to this time is associated with both false negative and false positive results.

The following may increase the risk of false negative UBT results, therefore, prior to testing, a patient must:

• fast and refrain from smoking for four hours,
• refrain from taking any antacid or symptomatic medication for at least two weeks,
• refrain from taking H2 inhibitors for one day,
• refrain from taking proton pump-inhibitor (Losec, Prevacid, Pantoloc) for at least three days,
• refrain from taking antibiotics for at least one month, and
• wait six weeks after H. pylori treatment.

References:

Veldhuyzen van Zanten SJO, et. al. An evidence-based approach to the management of uninvestigated dyspepsia in the era of Helicobacter pylori. Can Med Assoc J 2000; 162 Suppl 12: 3-23.

Bazzoli F, et. al. Urea breath tests for the detection of Helicobacter pylori infection.  Helicobacter 1997; 2 Suppl: S34-7.

Fallone CA, et.al. The urea breath test for Helicobacter pylori infection; taking the wind out of the sails of endoscopy.  CMAJ 2000 May 16; 162: 1401-2