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

Indications: - H pylori Clinical significance: - test for urease activity of Campylobacter-like organism (CLO) Specimen: biopsy from gastric antrum 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: 1) recent gastrointestinal bleeding 2) use of proton pump inhibitor* of H2 antagonists* 3) antibiotics or bismuth-containing compounds *Consider H pylori serology in patients on therapy with proton pump inhibitor or H2 blocker.

General

clinical microbiology test

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 328
  2. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 342
  3. UpToDate 2004 http://www.uptodate.com