STORAGE-TEMPERATURE OF THE UNBUFFERED RAPID UREASE TEST

Objectives: The unbuffered rapid urease test (RUT) is an accurate, rap id, and inexpensive method for detecting Helicobacter pylori. However, it is generally recommended that the reagent be prepared daily, This prospective study was undertaken to evaluate the shelf life of our unb uffered RUT when stored at 4 and -20 degrees C, Methods: Ninety-five p atients were studied, Three sets of antral (X2) and body (X1) biopsy s amples were taken from each patient, The samples were subjected to his tological examination, with the RUTs stored at 4 and -20 degrees C, Th e RUT tubes were examined at 1 and 15 min, Results: Fifty-six patients (59%) were infected with H. pylori as defined by histological examina tion, The reagent was classified according to storage time (group I, l ess than or equal to 5 days; group II, >5 days), The mean (SD) storage time of group I (n = 59) and group II (n = 36) was 3.2 (1.4) and 9.9 (5.0) days, respectively, At 15 min, the sensitivity of our RUT stored at 4 degrees C was significantly higher in group I than in group II ( 92 vs 47%), On the other hand, the sensitivity of our RUT stored at -2 0 degrees C remained consistently high in both groups (15 min. group I , 92%; group II, 100%), Our RUTs stored at 4 and -20 degrees C were hi ghly specific in both groups, Conclusions: Our RUT remains highly sens itive and specific when it is stored at 4 degrees C for up to 5 days, When the RUT is expected to be stored for a longer period of time, the bottles should be frozen at -20 degrees C.