I. Gangaidzo et al., HELICOBACTER-PYLORI IN ENDOSCOPY PATIENTS IN ZIMBABWE - VALUE OF ENZYME-LINKED-IMMUNOSORBENT-ASSAY AND A RAPID UREASE TEST, Transactions of the Royal Society of Tropical Medicine and Hygiene, 89(5), 1995, pp. 502-505
Citations number
26
Categorie Soggetti
Public, Environmental & Occupation Heath","Tropical Medicine
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.