HELICOBACTER-PYLORI IN ENDOSCOPY PATIENTS IN ZIMBABWE - VALUE OF ENZYME-LINKED-IMMUNOSORBENT-ASSAY AND A RAPID UREASE TEST

Biopsy and serum specimens were obtained from 95 patients undergoing e ndoscopy at the University of Zimbabwe Medical School. Common presenti ng features were epigastric pain, bleeding and dyspepsia. Ulcers were detected in 16 patients (17%), and were more common in men (24%) than in women (7%). Histological examination of biopsies showed that all 95 patients had spiral-shaped organisms that were indistinguishable micr oscopically from Helicobacter pylori, though the numbers of organisms varied considerably. There was evidence that the degree of inflammatio n in the mucosa was related to the numbers of H, pylori-like organisms (HPLO) present. Fifty-one biopsy specimens (55%) gave a positive rapi d urease test (RUT), with colour change occurring within 4 h. In all b ut one case, the gastric mucosa from these patients contained moderate to numerous HPLO. We defined the 'gold standard' of H. pylori-associa ted gastritis as the presence of both moderate to numerous HPLO and mo derate to severe inflammation in the gastric mucosa. Using these crite ria, RUT had a sensitivity of 67% and a specificity of 68%. Sera from 99 patients were tested for immunoglobulin G antibodies reactive with a glycine-extract antigen of H. pylori, using an enzyme-linked immunos orbent assay(ELISA). Sera giving an indeterminate reaction in the ELIS A were also tested by Western blotting. In all, 36 sera (39%) gave a p ositive ELISA or Western blot reaction. There was poor correlation bet ween serology and RUT results, with only 57% of biopsy specimens from seropositive patients giving a positive RUT, compared with 45% from se ronegative patients. Positive serology was found in only 35 patients ( 61%) with histological evidence of H. pylori-associated gastritis, and the specificity of the test was only 54%. When used in combination wi th the RUT result, however, 79% of patients with a positive RUT and po sitive serology had histological evidence of H. pylori-associated gast ritis. There was a general trend for increased seroprevalence in patie nts with mild to moderate atypia. These findings indicate that serolog y, using an antigen derived from the type strain of H. pylori, is unre liable in detecting H. pylori infection in Zimbabwe. Current studies a re aimed at characterizing antigens from organisms isolated from Zimba bwean patients.