Helicobacter pylori infection diagnostic tests

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Yamuna Kondapally, M.B.B.S[2]

Endoscopic diagnostic tests are biopsy-based diagnostic methods for H. pylori infection. These include histology, rapid urease testing, culture and polymerase chain reaction (PCR).

Endoscopic diagnostic tests are biopsy-based diagnostic methods for H. pylori infection. This include:

• Histology
• Rapid urease testing
• Culture
• Polymerase chain reaction

• Histology for H. pylori detection depends on:^[1]

• Site, number, and size of gastric biopsies
• Method of staining
• Level of experience of the examining pathologist

• Advantage of histology over other diagnostic studies is its ability to detect the pathological changes associated with H. pylori infection such as inflammation, atrophy, intestinal metaplasia, and malignancy.^[2]
• Multiple biopsies are required for accurate diagnosis as the prevalence and density of H. pylori varies throughout the stomach. Therefore a minimum of three biopsies is taken from different sites. They are:^[1][3]

• Angularis
• Greater curvature of the corpus
• Greater curvature of the antrum

• The sensitivity of histology is greatly affected by the use of medications such as bismuth, antibiotics, and PPI.^[4]

• Identifies active H. pylori infection through the organism's urease activity.^[5]
• Procedure

• The gastric biopsies obtained are placed into an agar gel or on a reaction strip containing urea, a buffer, and a pH-sensitive indicator.
• The urea is metabolized to ammonia and bicarbonate in the presence of H. pylori's urease leading to a pH increase in the microenvironment of the organism.
• A change in color of the pH sensitive indicator signifies the presence of the active infection.

• The sensitivity of the RUT decreases due to medications such as bismuth-containing compounds, antibiotics, or PPIs which reduce the density and/or urease activity of H. pylori.^[6]
• It is recommended that biopsies are taken from two sites due to the patchy distribution of H. pylori infection after antibiotics use. The sites include:^[7][4]

• The body at the gastric angularis
• Greater curvature of the antrum

• PPIs are withheld for 1-2 wk before the performance of RUT as they reduce the sensitivity of the test.^[8]

• Culture is not as sensitive as RUT or histology.^[9][10]
• Highly specific method for identifying active H. pylori infection.
• It is also used to determine antibiotic sensitivities and resistance.

• PCR is highly specific and more sensitive than other biopsy-based diagnostic techniques.^[11]
• It is also used to identify mutations associated with antimicrobial resistance.^{[12][13][14][15]}
• This method is not standardized across laboratories