Campylobacter-like organism (CLO) test (rapid urease assay, Pylori-Tek, Hp-fast)

Indications

• H pylori

Principle

• one or 2 pieces of tissue are placed in an agar well containing urea & a pH indicator
• urease derived from H pylori (or Campylobacter-like organism) cleaves urea & releases NH3 & CO2

urea + H2O -> 2 NH3 + CO2

NH3 + H2O -> NH4+ + OH-

• the increased pH from release of NH3 results in a color change.
• positive results may be apparent in 1 hour.
• a final reading is obtained after 24 hours.

Sensitivity: 90-95%

Specificity: 95-100%

False negatives may occur with:

• recent gastrointestinal bleeding
• use of proton pump inhibitor* of H2 antagonists*
• antibiotics or bismuth-containing compounds

*Consider H pylori serology in patients on therapy with proton pump inhibitor or H2 blocker.

Clinical significance

• test for urease activity of Campylobacter-like organism (CLO)

Specimen

biopsy from gastric antrum

More general terms

• clinical microbiology test