Evaluation of a modified medium for the one hour urease test for Helicobacter pylori infection.

ABSTRACT

The biopsy urease test is a simple and rapid method for the diagnosis of Helicobacter pylori infection; results are obtained within 4 h to 24 h. Various modifications of the media used in this test have been tried, to improve the accuracy and speed of the test. We compared the yield obtained with two media the standard Christensen's urea medium and a modified plain urea medium (without the nutrients glucose and peptone); the result was read upto 1 h. In the first 53 cases, culture was obtained when either of the media gave a negative result. There was no difference in false positives in the two media, while there were more false negatives with the plain urea medium (4) compared to the Christensen's medium (1). In the latter 69 patients, we determined the accuracy of the two media by obtaining culture in all cases. The Christensen's medium had a sensitivity of 100% and a specificity of 92.1%, while the plain urea medium had a sensitivity of 96.7% and a specificity of 92.1%. The speed of reaction in both media was similar. We conclude that the Christensen's urea medium gives accurate results even when read at 1 h; the plain urea medium gives similar results.