Diagnosing H. pylori: Tests and Procedures Explained

Helicobacter pylori (H. pylori) is a common bacterium that infects the stomach's lining and is implicated in various gastrointestinal diseases, including ulcers and gastritis. Despite its prevalence, detecting and managing H. pylori infections remains challenging. 

This article aims to provide healthcare practitioners with a detailed overview of the diagnostic methods available for identifying H. pylori, ranging from noninvasive tests to invasive procedures. By understanding these techniques, practitioners can better diagnose and treat infections, potentially preventing more serious gastrointestinal diseases.

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What is H. pylori and What Are Its Health Implications?

H. pylori is a gram-negative bacterium that infects the stomach lining and has been implicated in numerous gastrointestinal diseases. It is highly prevalent globally, affecting up to 50% of people. 

Although carriers of H. pylori can be asymptomatic, some infections can lead to inflammation and diseases such as gastritis, peptic ulcer disease, duodenal ulcer disease, gastric cancer, and MALT lymphoma (18,20).

Transmission of H. pylori occurs through numerous routes, including oral-oral and oral-fecal, and thus commonly occurs between family members and in areas where adequate sanitation is not accessible (20).

H. pylori is well suited to infect and survive the gastric environment in humans. It releases a compound called urease, which alters the pH in the area directly surrounding the bacterium, effectively buffering against the stomach's acidity, which would otherwise cause damage (18). 

It has a small "tail" called a flagella that allows it to propel itself toward the cells of the stomach lining, where it attaches and colonizes, leading to infection. Once attached, H. pylori releases toxins that damage local tissues (20), leading to inflammation and disease development.

Symptoms of Infection 

Although many carriers of H. pylori do not experience symptoms, symptoms can occur once the infection leads to inflammation. These include:

• Burning abdominal pain
• Loss of appetite
• Nausea and/or vomiting
• Indigestion
• Acid reflux and heartburn
• Gas and bloating
• Frequent burping
• Iron deficiency anemia

Diagnostic Tests for H. pylori

Testing for H. pylori may involve invasive tests that require an endoscopy or noninvasive tests that rely on stool, breath, or blood samples (17). 

Noninvasive Tests

Urea Breath Test (UBT)

The urea breath test (UBT) has been used for over 30 years and is the most reliable noninvasive testing option for H. pylori. To perform this test, a patient ingests a urea solution in pill or liquid form and undergoes a breath test 15 minutes later.

H. pylori metabolizes the urea and releases carbon dioxide as a byproduct, which is then measured to determine if infection is present. The UBT is highly accurate, with a 95% sensitivity and specificity rate (22).

Medications such as proton-pump inhibitors (PPIs), bismuth, antibiotics, and herbal antibiotics can lead to inaccuracies in testing, so they should be avoided for 2-4 weeks before testing. Additionally, gastrointestinal bleeding from ulcers can interfere with UBT results, and it is recommended to delay testing until bleeding has resolved.

Stool Antigen Test (SAT)

The SAT uses fecal samples to look for H. pylori antigens. It is highly sensitive and specific for detecting H. pyloriinfections and does not involve costly or invasive procedures. 

Like the UBT, the accuracy of the SAT can be affected by recent antibiotic or PPI use and upper gastrointestinal bleeding and should be delayed in the presence of these. Irregular bowel movements may also affect accuracy (22). 

In addition to SAT, it is possible to test for H. pylori in the stool using PCR techniques that detect the presence of bacterial DNA and can provide more detailed genetic information about the specific genotypes of the bacteria present (22). 

Serology

Blood tests that detect the presence of anti-H pylori IgG antibodies can also indicate present or recent H. pylori infection. 

However, because IgG antibodies can persist in the bloodstream well after an infection has resolved, the serology tests cannot distinguish between past and current infections, making it less desirable than the UBT and SAT for clinical diagnostic purposes. 

The advantage of the H. pylori blood test is that it is unaffected by gastrointestinal bleeding and PPI, antibiotic, or bismuth use (22). 

Invasive Tests 

Endoscopy with Biopsy

All invasive testing starts with an endoscopy, a procedure in which an instrument is inserted into the stomach and duodenum of the small intestine to visualize the gastrointestinal lining. 

Biopsies (small tissue samples) are taken from the gastric mucosa during this procedure. These samples are then further examined and tested for the presence of H. pylori using PCR testing or one or more of the methods below. 

Because endoscopies are invasive and costly, they are generally reserved for testing for more severe manifestations of H. pylori infection, such as gastrointestinal bleeding, suspected peptic or duodenal ulcers, gastric cancer, and MALT lymphoma (17,22). 

When assessing for H. pylori infection, most biopsy samples are taken from the antrum and corpus of the stomach (22).

Histology

Histology is considered the gold standard for direct H. pylori testing. Once tissue samples are obtained by biopsy, they are treated with specific stains that make it easier to visualize the presence of H. pylori cells. These samples are then examined under a microscope to detect infection. 

Like the UBT and SAT, histological examination is vulnerable to the recent use of PPIs and antibiotics, so these medications should be avoided for at least 2-4 weeks before the biopsy samples are taken. 

Additionally, H. pylori infections are often distributed unevenly throughout the stomach lining. So, these cells can only be detected if biopsies are taken in H. pylori-concentrated areas (22). 

Culture

Culturing H. pylori involves placing a biopsy sample into a growth media and incubating it to assess for H. pylori cell growth. Although culture studies can be more susceptible to human and laboratory error, they have the distinct advantage of being able to test for antibiotic sensitivity to help guide treatment options. Culture and sensitivity studies are recommended in areas where clarithromycin resistance exceeds 20% (22). 

Rapid Urease Test (RUT)

RUT is a quick, inexpensive, and reliable method of identifying H. pylori infections in tissue samples. This test uses a urea test reagent that converts to ammonia in the presence of H. pylori, causing a notable increase in pH levels, detected using a pH monitor. 

The main disadvantage of an RUT is its poor accuracy in the presence of gastric bleeding, so it should not be the sole indicator used in these cases (22). 

How to Choose the Right Diagnostic Test

With a multitude of options to choose from, it can take time to determine which test is most appropriate for a patient. Due to the ease, accuracy, and noninvasive nature of the UBT and SAT, these tests can be helpful in pediatric patients when endoscopies are not otherwise warranted. 

The UBT and SAT are also appropriate for testing in adults when symptoms are not severe and more serious diseases such as bleeding ulcers, gastric cancer, and MALT lymphoma are not suspected or have been previously ruled out (22). However, endoscopies are required for diagnostic workup if these diseases are suspected. 

Additionally, the UBT and SAT are often employed to monitor treatment efficacy to ensure that H. pylori eradication is complete. For these purposes, waiting 2-4 weeks post antibiotic, bismuth, and PPI use is essential to enhance testing accuracy (20). 

How to Treat H. pylori Based on Diagnosis

If testing confirms an active H. pylori infection in the presence of symptoms, treatment of the infection is often recommended. First-line treatment options are focused on the eradication of H. pylori and include a combination of antibiotics, PPIs, and sometimes bismuth taken together or sequentially:

• Clarithromycin triple therapy: The standard first-line treatment for H. pylori, this therapy combines PPI, clarithromycin, amoxicillin, and metronidazole for 14 days. It should only be undertaken when clarithromycin resistance is less than 15%.
• Bismuth quadruple therapy: PPI, bismuth, tetracycline, and nitroimidazole in combination for 10-14 days. This treatment option is suitable for those with penicillin allergies and high clarithromycin resistance. 
• Concomitant therapy: PPI, clarithromycin, amoxicillin, and nitroimidazole taken together for 10-14 days. Evidence suggests that this therapy has the highest eradication rates among the conventional first-line treatment options. 

Including culture antibiotic sensitivity analysis in the diagnostic workup can help guide which antibiotics would be most effective for treatment and which would likely lead to resistance. 

Follow-up testing via a UBT or SAT is often performed to ensure that a prescribed treatment effectively eradicates the H. pylori infection (20). 

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Key Takeaways

Accurate diagnosis of H. pylori is essential for effective patient management, as it guides appropriate treatment strategies that can prevent severe gastrointestinal complications.

Healthcare practitioners should prioritize staying updated with the latest diagnostic technologies and guidelines developments.

This commitment to continual learning will enhance their ability to detect H. pylori accurately and improve overall clinical outcomes for their patients.