The urease test is a laboratory test used to identify bacteria by detecting the activity of an enzyme that the bacteria may or may not have. Urease is an enzyme responsible for the breakdown of urea into ammonia and bicarbonate, which lowers the pH of the place where it is present and favors its proliferation.
This test is mainly used in the diagnosis of infection by Helicobacter pylori , or H. pylori , which is responsible for several problems, such as gastritis, esophagitis, duodenitis, ulcer and stomach cancer, for this reason. Thus, if H. pylori infection is suspected, the gastroenterologist can perform the urease test during endoscopy. If so, treatment is started quickly with the aim of preventing the disease from developing and relieving the person's symptoms.
How the test is done
The urease test is carried out in the laboratory through the analysis of the collected material, with the isolation of the microorganism being carried out and biochemical identification tests, among them the urease test. To perform the test, the isolated microorganism is inoculated into the culture medium containing urea and the phenol red pH indicator.
The result is considered positive when the bacterium that has the enzyme urease is able to degrade urea, giving rise to ammonia and bicarbonate, and this reaction is perceived by changing the color of the medium, which changes from yellow to pink / red. On the other hand, the urease test is negative when there is no change in the color of the medium, indicating that the bacteria does not have the enzyme. It is important that the results are interpreted within 24 hours so that there is no chance of false-positive results, which are those that due to the aging of the medium, urea starts to be degraded, which can change the color.
In the case of the urease test to detect H. pylori infection , the test is performed during the high endoscopy exam, which is an exam that assesses the health of the esophagus and stomach, without causing pain or discomfort to the patient and the result can be evaluated in a few minutes. During the examination, a small piece of the stomach wall is removed and placed in a flask containing urea and a pH indicator. If after a few minutes the medium changes color, it is said that the test is urease positive, confirming infection by H. pylori . See what symptoms may indicate an infection with H. pylori .
In addition to identifying the infection by Helicobacter pylori , the urease test is done to identify several bacteria, and the test is also positive for Staphylococcus saprophyticus , Staphylococcus epidermidis , Proteus spp. and Klebsiella pneumoniae, for example.
How to prepare for the test
If the urease test is done normally in the laboratory routine, no preparation is necessary for the exam. However, if performed during endoscopy, it is important that the person follows all the rules of the exam, such as avoiding using antacid medications and fasting for at least 8 hours.
The performance of the urease test during endoscopy is important for the doctor to establish the best form of treatment, especially in the case of ulcers, for example.
