Helicobacter pylori

Test codes:
B0021 - Ultrasensitive qualitative detection of Helicobacter pylori by real time polymerase chain reaction
P0010 - Ultrasensitive Helicobacter species screen by nested polymerase chain reaction
P0011 - Ultrasensitive Helicobacter species identification by nested polymerase chain reaction and restriction fragment length polymorphism

Helicobacter pylori is a gram-negative spiral bacterium found in gastric mucosa and associated with active and chronic gastritis. H. pylori can establish a chronic, persistent infection, which may lead to gastric or duodenual ulcers, gastric cancer and gastric lymphomas. Studies have revealed that approximately 50% of the world’s population is infected with H. pylori.

Biochemically, the bacterium produces catalase, oxidase and urease enzymes. The urease enzyme permits the bacterium to metabolize urea present in the gastric mucosa and establish a microenvironment favorable to the organism. H. pylori is a highly motile organism with multiple unipolar flagella. Both the urease enzyme and the flagella are considered to be important virulence factors.

Diagnosis of Helicobacter pylori infection in humans relies on upper endoscopy or the 13C-urea breath test (see review by Nakamura, 2001). Although the endoscopy procedure permits culture of the bacterium from biopsy specimens (the gold standard for diagnosis), demonstration of urease activity and histological detection of the germ, the procedure is expensive and invasive. The 13C-urea breath test is a well-established, relatively sensitive, specific and noninvasive method. Molecular tests, such as PCR, can also offer precise diagnosis of H. pylori infections. In fact, molecular testing by PCR can complement other diagnostic tests because it can be applied to archival fixed tissue, environmental samples, gastric juice, oral secretions, and stool samples, in which traditional diagnostic tests do not have sensitivity and perform poorly. Studies have shown than PCR detection of H. pylori in gastric juice specimens can reach a sensitivity of 96 % and a specificity of 100 % (Westblom et al., 1993; Yoshida et al., 1999). This capability is especially useful in monitoring active H. pylori infection in primates and other animals, as the breath test is difficult to conduct for these animals.

Utilities:

• Confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of H. pylori infection
• Ensure that animal colonies are free of H. pylori
• Early prevention of spread of this bacterium among a colony
• Minimize personnel exposure to this bacterium
• Safety monitoring of biological products and vaccines that derive from animals

References:
Nakamura, R.M. (2001) Laboratory tests for the evaluation of Helicobacter pylori infections. J. Clin. Lab. Analysis 15: 301-307.
Westblom, T.U., Phadmis, S., Yang, P. and Czinn, S.J. (1993) Diagnosis of Helicobacter pylori infection by means of a polymerase chain reaction for gastric juice aspirates. Clin. Infect. Dis. 16: 367-371.
Yoshida, H., Maeda, S. and Ogura, K. (1999) PCR-monitoring of gastric juice obtained with the capsulated string for evaluation of H. pylori infection. Nippon Rhinsho 57: 107-110.

Specimen requirement: 1 ml gastric lavage or feces or tissue shipped overnight at room temperature; or tissue shipped frozen.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time PCR

Normal range: Nondetected