Admixture with whole blood does not explain false-negative urease tests.

Area of Science:

• Gastroenterology
• Clinical Microbiology
• Diagnostic Testing

Background:

• Rapid urease tests (RUTs) are commonly used for Helicobacter pylori detection.
• Reduced RUT sensitivity is observed in patients with active upper gastrointestinal bleeding (UGIB).
• The in vitro effect of whole blood on RUT performance remains unclear.

Purpose of the Study:

• To investigate the in vitro impact of whole blood on the sensitivity and accuracy of rapid urease testing for H. pylori.
• To determine if blood admixture contributes to false-negative RUT results in UGIB.

Main Methods:

• Urease solution was mixed with saline and heparinized whole blood (H. pylori antibody-positive and -negative).
• Mixtures were serially diluted in saline and/or whole blood.
• Admixtures were tested using three different rapid urease kits.

Main Results:

• Whole blood admixture, particularly in H. pylori-seropositive blood, enhanced RUT performance up to fourfold compared to saline alone.
• No false-negative results were observed in any tested kit due to whole blood admixture.
• Both H. pylori antibody-positive and -negative whole blood accelerated the urease reaction in vitro without adverse impact.

Conclusions:

• Whole blood accelerates the urease reaction in vitro, potentially improving RUT performance.
• Admixture with whole blood does not appear to cause false-negative RUT results.
• The reduced sensitivity of RUT in active UGIB is likely due to factors other than whole blood interference.