Abstract

The presence of C pylori infection was determined in 1445 patients undergoing upper gastrointestinal endoscopy over a 12 month period. The presence of C pylori was detected in gastric mucosal biopsy specimens by the biopsy urease test, microscopy (Gram stained smears and histology) and culture. Two media were used for the biopsy urease test: Christensen's urea broth (for the first 600 patients) and the Christensen's urea broth modified by increasing the concentration of phenol red and omitting the nutrients, glucose and peptone (for the remaining patients). Both the Christensen's urea broth and modified urea broth were almost 100% specific when compared with detection of C pylori by Gram, culture and histopathology. The modified broth was more sensitive (96% sensitivity compared with culture) than the Christensen's broth (92% sensitivity) but this difference was not statistically significant. The modified broth gave significantly more positive results (58%) in less than 30 minutes than the Christensen's broth (48%). Seventy four per cent of positive results were available in less than two hours. Specimens from patients with extensive C pylori infection gave more rapid results: 86% of specimens that yielded a profuse growth of C pylori and 76% that contained numerous organisms on histological sections had a positive urease test in less than one hour. There was no significant difference between the specificity and sensitivity of our modified urea broth and the other modified broths described in the literature. This test is a cheap and rapid alternative to the diagnosis of C pylori by Gram stained smears or culture.