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Journal of Clinical Microbiology, Mar 1996, 530-533, Vol 34, No. 3
AP Lage, A Fauconnier, A Burette, Y Glupczynski, A Bollen and E Godfroid
A very simple, practical, sensitive, and specific colorimetric
hybridization assay for detecting amplified Helicobacter pylori DNA is
described. This assay, which combines a sensitive sandwich DNA
hybridization reaction and a colorimetric protocol similar to those used in
conventional enzyme immunoassays, was shown to be suitable for detecting H.
pylori-infected gastric biopsy specimens and for monitoring the eradication
of the pathogen after treatment. The specificity and sensitivity of the
colorimetric hybridization assay were tested by assaying 27 H. pylori
strains (4 reference and 23 clinical isolates), 9 strains of other
Helicobacter spp. or Campylobacter spp., and 11 clinical isolates of other
urease-positive bacteria. The likelihood of H. pylori detection in gastric
biopsy specimens by the colorimetric hybridization assay was evaluated with
23 H. pylori-positive and 41 H. pylori-negative biopsy specimens on the
basis of positive and negative results, respectively, of culture, rapid
urease test, histological examination, and PCR. Biopsy specimens from 33
treated patients, endoscopied 4 to 8 weeks after the end of treatment, were
also tested. All H. pylori strains showed positive results in the
colorimetric hybridization assay, presenting optical densities at 450 nm
(OD450S) of > or = 3.0. None of the other Helicobacter spp.,
Campylobacter spp., or the clinical isolates of other urease-positive
bacteria showed OD450S equal to or greater than the cutoff (mean OD450
cutoff, 0.208). The colorimetric hybridization assay detected all 23 H.
pylori-positive biopsy specimens (mean OD450, 2.910 +/- 0.295), while none
of the H. pylori-negative biopsy specimens was shown to be positive in the
assay (mean OD450, 0.108 +/- 0.025). H. pylori was considered to be not
eradicated from three of the posttreatment biopsy specimens by culture,
rapid urease test, histological examination, and PCR. They were all
positive by the colorimetric hybridization assay, and their OD450S were
> or = 3.0. The colorimetric hybridization assay also detected two other
H. pylori- positive patients. Specimens from these two patients had
negative culture, rapid urease test, and histology results, and a specimen
from one of them also tested negative by PCR. These results indicate that
the colorimetric hybridization assay is a suitable method both for the
diagnosis of H. pylori in biopsy specimens and for the follow-up of
patients after the end of treatment.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
Rapid colorimetric hybridization assay for detecting amplified Helicobacter pylori DNA in gastric biopsy specimens
Service de Genetique Appliquee, Universite Libre de Bruxelles, Belgium.
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