Introduction:
Helicobacter pylori (H. pylori) is a gram-negative, spiral-shaped bacterium implicated in the pathogenesis of peptic ulcer disease, gastritis, and gastric carcinoma. The Rapid Urease Test (RUT) is a commonly used, cost-effective, and quick diagnostic test to detect the presence of H. pylori in gastric mucosal biopsies.
Principle:
H. pylori produces large amounts of the enzyme urease, which hydrolyzes urea into ammonia and carbon dioxide.
- Ammonia raises the local pH.
- The RUT uses a urea-containing medium with a pH indicator (usually phenol red).
- If H. pylori is present, the urease breaks down urea, and the pH increase causes a color change from yellow to pink/red.
Procedure:
- Sample Collection:
- A gastric mucosal biopsy is obtained during upper GI endoscopy, usually from the antrum.
- Application:
- The biopsy is placed in the RUT medium (like CLO test, Pronto Dry, or HpFast).
- Result Interpretation:
- Positive Test: Color change to pink/red, usually within 30 minutes to 2 hours.
- Negative Test: No color change after the recommended incubation time (often up to 24 hours).
Advantages:
- Rapid results
- High specificity (>90%)
- Inexpensive and easy to perform
- Useful for point-of-care testing
Limitations:
- False negatives may occur if:
- Patient is on proton pump inhibitors (PPIs), antibiotics, or bismuth
- In atrophic gastritis or intestinal metaplasia
- Sensitivity varies (85–95%) depending on the bacterial load
Clinical Applications:
- Used for initial diagnosis of H. pylori infection during endoscopy
- Helps guide eradication therapy
- Often combined with histology or culture for confirmation
Conclusion:
The Rapid Urease Test is a fast, specific, and affordable diagnostic tool for detecting H. pylori infection directly from gastric biopsies. While highly useful in clinical practice, results must be interpreted alongside clinical findings and with awareness of possible interfering factors like recent medication use.