The Changing Landscape of H. Pylori Diagnosis in RQHR

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The Changing Landscape of H. Pylori Diagnosis in RQHR

25-May-2017

As you may already be aware, Helicobacter pylori stool antigen test (H. pylori SAT) will be available in RQHR starting June. This test is meant to replace the Urea Breath Test and the H. pylori serology for the routine diagnosis of H. pylori.

There have been a number of questions from practitioners about this test which I wish to highlight here.

 Question 1. What is the H. pylori SAT detecting?

Answer. In the active phase of H. pylori infection, protein parts (a.k.a antigens) of the bacterium are shed into the stool and are detected by the test

Question 2. Should I still order H. pylori serology for routine diagnosis of H. pylori infection?

Answer. No.

Serology should no longer be routinely ordered for the diagnosis of H. pylori. The reason for this is that a positive H. pylori serology result CANNOT be used to definitively establish an active H. pylori infection. A positive result signifies that a person has, at some point in their life, been exposed to the H. pylori bacterium. Since then, they may have cleared the organism or may have been effectively treated for the disease. Despite this, their serology results will likely remain positive for life.

H. pylori stool antigen, on the other hand, is going to be positive during active infection and will be negative after the organism has been eradicated post effective antibiotic therapy.

Question 3. Can I order this test to check if the antibiotic therapy was successful in eradicating the H. pylori infection?

Answer. Yes.

One of the advantages of H. pylori SAT over H. pylori serology is that H. pylori SAT will be negative after successful eradication of the bacterium post effective antibiotic therapy whereas H. pylori serology in most cases remains positive for life (See answer to question 1 for more details)

Question 4. Are there any special instructions I should give to patients prior to specimen collection?

Answer. Yes.

Please discuss with your patient the timing of stool collection to ensure that ALL antibiotics are discontinued a minimum of 28 days prior to testing and, Proton pump inhibitors (PPIs) as well as bismuth containing preparations such as Pepto-Bismol, are discontinued a minimum of 14 days prior to testing. Please note, histamine blockers or H2 antagonists ex. Pepcid, Tagamet, Axid and Zantac, can be used as alternative means of acid suppression during this time.

An instruction sheet for specimen collection containing these timelines along with a sterile container will also be provided at all outpatient lab locations. Reinforcing this concept is very important as the collection of an inappropriately timed specimen may lead to a FALSE NEGATIVE RESULT and a potential delay in treatment.

Question 5. When I ordered H. pylori SAT previously, the specimen was rejected because it was not frozen. Do I have to instruct the patients to freeze the stool sample prior to submission?

Answer. No.

H. pylori SAT testing will take place locally and stools DO NOT need to be frozen. Fresh stool specimens should be promptly submitted to the lab and, if a delay of >4hrs is anticipated, stools can be refrigerated prior to submission. Ideally, all specimens should be submitted within 24 hrs of collection.

Question 6. What container should the specimen be submitted in?

Answer. Any sterile container.

 Stool should not be contaminated with toilet water, urine or toilet paper therefore, it is best to initially collect it into a plastic or cardboard container and transfer the desired amount, about 1 gram of formed stool or a tablespoon of diarrheal stool, into a sterile container such as the orange top container used for urine collection. These instructions will be provided to patients at the outpatient lab locations.

Question 7. Are there patients for whom I should NOT order an H. pylori SAT?

Answer. Although it is the diagnostic test of choice for persons with symptoms of peptic ulcer disease such as indigestion, abdominal pain or bloating, nausea or vomiting, IT SHOULD NOT REPLACE AN ENDOSCOPIC EXAMINATION in patients that have urgent or severe symptoms such as gastric bleeding or signs of possible malignancy.

Question 8.  Which box should I check off on the RQHR microbiology requisition to order the H. pylori SAT?

Answer. H. pylori SAT is not specifically listed on the RQHR microbiology requisition, therefore, youMUST SPECIFY it in the“OTHER/SPECIAL REQUESTS” box in the right lower corner (see picture) of the requisition.

For questions or more information, please contact the microbiology laboratory at (306) 766-4481 or the Microbiologist on-call through the hospital switchboard.