Helicobacter pylori has been shown to cause active chronic gastritis and has been implicated as a primary etiologic factor in duodenal ulcer disease, gastric ulcer and non-ulcer dyspepsia. By causing chronic inflammation, H. pylori may weaken the mucosal defenses and allow acid and pepsin to disrupt the epithelium.

H. pylori produces large amounts of urease enzymes. The CLOtest (Ballard Medical Products) detects the urease enzyme of H. pylori in gastric mucosal biopsies.


CLOtest is a sealed plastic slide holding an agar gel, which contains urea and other components. If the urease enzyme of H. pylori is present in an inserted tissue sample, the resulting degradation of urea cause the pH to rise causing a reaction of the gel, which is interpreted by the Pathologist.

CLOtest should be stored in the refrigerator at 2 - 8ºC / 36 - 48ºF. CLOtest has a shelf-life of 18 months when properly refrigerated.


Patients should not have taken antibiotics or bismuth salts for at least 3 weeks prior to endoscopy. Suppression of H. pylori by these agents makes the organism difficult to detect by any means, and re-growth of H. pylori patchy, leading to false negative results in the first few weeks after treatment.


Before use, the CLOtest should be examined to make sure that the well is full and is a yellow color. If a CLOtest is any color but yellow, it should not be used. If this should happen, proceed with another CLOtest slide or call WPM Pathology Laboratory.

Before the endoscopy, warm the slide to room temperature (20 - 30ºC). Warming will help the test work faster.


  1. A biopsy sample for CLOtest may be taken as soon as the physician has examined the stomach. The usual area to biopsy is the antrum, along the greater curve.
  2. Biopsy area of normal looking tissue rather than an area affected by erosions or ulceration. This is because H. pylori may be present in smaller numbers if the epithelium is eroded or the mucus layer is denuded. The standard biopsy forceps will provide a specimen of sufficient size (1 - 3mm diameter).
  3. If the biopsy specimen appears to be very small, it may be worthwhile taking a second biopsy and inserting both specimens into the CLOtest. Be careful not to contaminate the second specimen with blood from the first biopsy site.


  1. Turn the CLOtest slide so that the label is facing up and you do not see the well with the yellow gel.
  2. Peel the label away from the plastic slide so that you can see the yellow gel. Do not remove the label.
  3. With a sterile needle, take away the biopsy sample from the biopsy forceps and push it into the yellow CLOtest gel. Make certain that the biopsy sample is buried in the gel so that it will have the most contact with the gel.
  4. Re-seal the CLOtest label by pressing the label back on the plastic slide, so that the gel is covered.
  5. Write the name of the patient, the date, and the time that the biopsy sample was placed in the CLOtest gel, on the label.


Submit the CLOtest slide, along with a properly filled out WPM SURGICAL PATHOLOGY AND NON-GYN CYTOLOGY request form. Under Special Requests: indicate [X] Other, and write in “CLOtest”. Place in specimen transport bag for transportation to WPM Pathology Laboratory.


A “SURGICAL PATHOLOGY REPORT” will be issued by a Pathologist with the results from the CLOtest. A positive report indicates, with a 97% specificity, that H. pylori was present in the biopsy specimen.

False negatives may occur when very low numbers of H. pylori are present, or the bacterium has a patchy distribution (not present in the antrum), or with widespread intestinal metaplasia.

contact us

  • WPM Pathology Laboratory
  • 338 N. Front St.
  • Salina, KS 67401
  • 785.823.7201