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Test for Helicobacter pylori in gastric biopsy specimens

using SERIM PyloriTek test kit

 

 

PRINCIPLE                            H. pylori produces the enzyme urease which is not present in mammalian tissue.  The PyloriTek Test Kit detects urease activity in gastric biopsy specimens according to the following reaction:
                                       Urease
            Urea  +   H2O     -----------        2 NH3  +  CO2

The ammonia produced is detected with a pH indicator (bromophenol blue) which turns from yellow to blue at an elevated pH.

 

CLINICAL UTILITY                The test is used as an aid in the presumptive identification of H. pylori infection in patients with clinical signs and symptoms of gastrointestinal disease.

 

SPECIMEN                            PyloriTek Reagent strips allow individual testing of specimens from multiple areas of the stomach.  Recommendations concerning multiple specimen collection vary.  However, one specimen may be from the greater curvature of the pre-pyloric antrum.  A second specimen may be taken from the antral lesser curvature at or near the incisura.  H.pylori infection may be found in a third biopsy from the greater curvature of the body of the stomach.  Avoid areas of erosion or ulceration.  Up to three biopsy specimens from one patient can be tested on one PyloriTek Reagent Strip.

                                                A recent report has indicated specimen size is not critical in obtaining satisfactory results.

SPECIMEN HANDLING PRECAUTIONS
The specimen must be transferred directly from the forceps to the Reaction Pad, as urease activity in infected specimens can be lost during transport or storage prior to testing.
Contamination of specimens with formalin (from biopsy forceps or other sources) can inhibit H. pylori urease activity and lead to false negative results.

 

NORMAL RANGE                  Negative

 

 

COMPUTER CODES            N/A

 

 

QUALITY CONTROL            A small red spot located in the upper left-hand corner of the Reaction Pad contains urease and provides an internal POSITIVE REACTIVE CONTROL.  An intense purple or blue spot will develop over the POSTIIVE REACTIVE CONTROL within 60 minutes after the test is started.


 

 

                                                Failure of the purple or blue spot to appear indicates that the test has not developed properly.  This is an invalid test.   Perhaps the Hydration Reagent was not applied to the Substrate Pad or the strip was not properly inserted into the reaction device.

 

                                                Since urease is present only in the POSITIVE REACTIVE CONTROL and in infected biopsy specimens,  the absence of purple or blue control in any other areas of the  REACTION PAD serves as a negative control.

                                                Development of purple or blue color in these other areas indicates that the strip has not reacted properly or has reacted due to exposure to excess heat, moisture or ammonia sources.

 

                                                SHOULD THE CONTROLS REACT INCORRECTLY, THE TEST IS INVALID AND THE RESULTS MAY NOT BE REPORTED.  Repeat testing on another reagent strip.  If problem persists, call the manufacturer (SERIM) at 1-800-542-4670 or email: customerservice@serim.com for advice.

 

 

CALIBRATION                       None required

 

PROCEDURE                        1.  Preparation of Test Strip

a.     Remove a test strip from the bottle, lay it down on a clean, dry surface. Turn the strip over.  Make sure the red Positive Reactive Control Spot is visible in the upper left-hand corner of the Reaction Pad.

b.   Write the patient name or Identification number and the time the test is started on the lines provided on the front of the strip.

c.   Turn the strip over and crease at the perforation.

d.   Add four drops of Hydration Reagent to the Substrate Pad (one drop in each corner of the absorbent pad at the end of the strip).

 

2.     Apply Specimen

a.     Using a clean applicator stick, plastic pick or any other suitable accessory, push the gastric specimen from the forceps onto the Reaction Pad.

b.     The specimen should be placed at least 6-7mm (1/4 “) from the red positive control spot which is visible on the Reaction Pad. 

c.     Specimens should be placed near the middle of the slightly raised area of the Reaction Pad which is on the opposite side from the yellow pH membrane.

d.     1, 2 or three specimens from the same patient can be placed on the pad.  Keep the specimens at least 6-7 mm apart to ensure that each reaction can be viewed separately.

 

3.      Fold and Insert Test Strip into Chamber

 When your gastric specimens are in place, fold the Substrate Pad on top of the Reaction Pad.  Immediately insert the folded strip, with the yellow side out, into the Reaction Chamber. Make sure the strip is fully inserted and touches the bottom of the reaction device.

 

4.     Interpret Results

a.     Within 60 minutes, examine the yellow Reaction Pad for the appearance of intense dark blue or purple color spots.  The purple positive control should appear in the upper right hand corner.   The positive control spot usually appears within 4-10 minutes but may occasionally take longer.

b.     Most positive patient specimens appear in less than 20 minutes.  Some very strong positives may appear in 1-2 minutes. 

NOTE:  A positive results may appear ANYTIME up to the full 60 minutes. 

                                                           c.   For a confirmed positive, BOTH specimen and positive control
                                                                   must show the strong blue/purple color.

d.   ALWAYS wait the full 60 minutes before reporting a patient’s results as NEGATIVE.


     

CALCULATIONS                   None

                                               

REAGENTS                           Kits are stored in the refrigerator at 2-7oC until the bottle of reagents is opened.  Allow all kit components to come to room temperature (15-30oC
or 59-86oF) prior to use.  Do not use kit pass the expiration date.  Once opened, store the kit components at room temperature.

 

1.      PyloriTek Reagent Strips

Substrate Pad:  3.3% Urea  

                                                Reaction Pad:    0.1% Bromophenol Blue, 0.2% Sulfamic Acid

                                                Store in the refrigerator at 2-7oC until the bottle is opened for use. Warm to room  temperature prior to use. Promptly replace and tighten cap after removing strip from bottle. DO NOT REMOVE desiccant, which keeps the strips protected from ambient moisture. Do not remove strip(s) from bottle until ready to use.  DO NOT RETURN any unused strips that have been exposed to ambient conditions to the bottle.  Indicate the date the bottle is opened on the bottle label.  DO NOT USE strips more than 3 months after the bottle has been opened, or after the kit expiration date, whichever occurs first.

 

                                                Avoid placing strips near sources of heat, ammonia (ammonia ampules, ammonia-containing cleaning compounds) or formaldehyde.  Extreme heat or chemical fumes may cause a change in the background color of the strip.

                                               

2.      PyloriTek Hydration Reagent

Contains:  1.8% Tris buffer

Store in the refrigerator at 2-7oC until the bottle of reagent strips is opened.  Allow all kit components to come to room temperature (15-30oC or 59-86oF) prior to use.

 

3.      PyloriTek Disposable Reaction Pouches

These are disposable plastic devices that serve as Reaction Chamber, which may be reused after thorough cleaning. (If reusing the Reaction chamber:  wash in warm soapy water using a mild detergent, rinse with clean water and dry with a fresh paper towel).  Reaction pouches provide solid contact between the gastric biopsy and the Substrate Pad and insures that the ammonia gas generated is directed through the membrane to the pH indicator. 

 

ALWAYS use the Disposable Reaction pouches to hold strips during the reaction time.  DO NOT USE tape or a paper clip.

Do not carry the pouches with developing tests in the pockets of your clothes during the one hour development time.  Consider the contents to be a potential biohazard.  Do not remove developing strips from the pouch or re-opening the strips.  This may affect the results.

                                               

 

LIMITATIONS OF                  PyloriTek Reagent Strips detect ammonia generated by H.pylori urease-

THE PROCEDURE               catalyzed hydrolysis of urea in the Substrate Pad A.  Ammonia can also be produced by tissue autolysis or can be found in blood as a waste product.  However, these non-specific reactions normally occur at a slower rate than can be detected visually in 60 minutes by the PyloriTek test.  It is possible that abnormal increases in these reactions may produce a pale blue or faint gray color over the specimen, which is a negative result.
Negative results may occur if an area is sampled which has not been colonized, particularly if the patient has been on antibiotic and/or bismuth salt therapy.
A positive test does not distinguish between colonization and a symptomatic infection.
The PyloriTek Test Kit is to be used to aid in diagnosis only with those patients with clinical symptoms of H.pylori infection.

 

 

 

REFERENCES                      PYLORITEK TEST KIT, package insert, SERIM Research Corporation, Elkhart, IN, website: serim.com





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