Helicobacter pylori (previously known as Campylobacter pylori) is a bacterium associated with gastritis, duodenal and gastric ulcers, and possibly gastric carcinoma. The healthcare provider orders this test when screening a patient for possible H. pylori infection. The organism is present in 95%–98% of patients with duodenal ulcers and 60%–90% of patients with gastric ulcers. A person with gastrointestinal symptoms with evidence of H. pylori colonization (e.g., presence of specific antibodies, positive breath test, positive culture, positive biopsy) is considered to be infected with H. pylori. A person without gastrointestinal symptoms having evidence of the presence of H. pylori is said to be colonized rather than infected.

This test detects H. pylori infection of the stomach. Traditionally, the presence of H. pylori has been detected through biopsy specimens obtained by endoscopy. As with any invasive procedure, there is risk and discomfort to the patient. Noninvasive methods of detection include the following:

1. Breath: Measures isotopically labeled CO₂ in breath specimens

2. Stool: H. pylori stool antigen test

The presence of H. pylori–specific IgG antibodies has been shown to be an accurate indicator of H. pylori colonization. ELISA testing relies on the presence of H. pylori IgG–­specific antibody to bind to antigen on the solid phase, forming an antigen–antibody complex that undergoes further reactions to produce a color indicative of the presence of antibody and is quantified using a spectrophotometer or ELISA microweld plate reader. The sensitivity is 94% and specificity 78%, compared with an invasive procedure, such as biopsy, for which the sensitivity is 93% and specificity 99%.

• Negative for H. pylori by ELISA indicates no detectable IgG antibody in serum or stool.

• A positive result indicates the presence of detectable IgG antibody in serum or stool.

1. Collect a 7-mL blood serum sample in a red-topped tube. Observe standard precautions. Label the specimen with the patient’s name, date, and test(s) ordered and place in a biohazard bag for transport to the laboratory.

2. Be aware that a random stool specimen may be ordered to test for the presence of H. pylori antigen.

3. The urea breath test (UBT) is a complex procedure and requires a special kit. Ensure that the collection balloon is fully inflated. Transfer the breath specimen to the laboratory. Keep at room temperature.

4. The ¹³C-urea breath test (¹³C-UBT) requires the patient to swallow an isotopically labeled (¹³C) urea tablet. The urea is subsequently hydrolyzed to ammonia and labeled CO₂ by the presence of H. pylori urease activity. After approximately 30 minutes, an exhaled breath sample is collected, and ¹³CO₂ levels are assessed using isotope ratio mass spectrometry.

1. This assay is intended for use as an aid in the diagnosis of H. pylori, and additionally, false-negative results may occur. The clinical diagnosis should not be based on serology alone, but rather on a combination of serology (and breath or stool tests), symptoms, and gastric biopsy–based tests as warranted.

2. The stool antigen test is used to monitor response during therapy and to test for cure after treatment.

Pretest Patient Care

1. Explain test purpose, procedure, and knowledge of signs and symptoms and risk factors for transmission: close living quarters, many persons in household, and poor household sanitation and hygiene. The patient swallows a capsule before a breath specimen is obtained. The serum antibody test would be appropriate for a previously untreated patient with a documented history of gastroduodenal ulcer disease and unknown H. pylori infection status.

2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.