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Journal of Clinical Microbiology, November 1998, p. 3285-3290, Vol. 36, No. 11
Laboratoire de Bactériologie,
Hôpital Pellegrin, 33076 Bordeaux Cedex, France
Received 27 April 1998/Returned for modification 23 July
1998/Accepted 18 August 1998
When the standard procedure for determining antibiotic
susceptibility of bacteria is used, the results are delayed, especially for bacteria that grow slowly, such as Helicobacter pylori.
Treatment for this bacterium may involve clarithromycin, a compound for which resistance has been associated with point mutations on the 23S
rRNA gene. This resistance is currently found in organisms isolated
from 0 to 15% of patients and jeopardizes the success of the
treatment. We have designed a test involving amplification and
colorimetric hybridization in the liquid phase to detect the mutation
at the molecular level. First, four reference strains, including the
wild type and three strains with the mutations A2143C, A2143G, and
A2144G, were used to optimize the method. Amplification was carried out
with primers previously published. The amplified products were added to
probe-coated microtiter wells. A DNA enzyme immunoassay was used to
detect the hybrids. The optimal conditions of the hybridization were
defined for each probe. Nineteen H. pylori strains
resistant to clarithromycin and 22 susceptible according to phenotypic
data were submitted to restriction with BsaI and
BbsI, and part of the 23S rRNA gene was sequenced in order
to determine the mutation involved for the resistant strains. The new
assay showed a complete correlation with the reference methods, except
for one strain. Cross-hybridizations as well as application of the
reaction to other bacteria did not lead to optical densities higher
than the cutoff values chosen with the receiving operating
characteristic curve. This method can be easily standardized and gives
a result within a day. Its application directly to the biopsy specimens
or infected gastric juice is planned in the future.
0095-1137/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Detection of Point Mutations Associated with
Resistance of Helicobacter pylori to Clarithromycin by
Hybridization in Liquid Phase
*
Corresponding author. Mailing address: Laboratoire de
Bactériologie, Hôpital Pellegrin, Place Amélie
Raba-Léon, 33076 Bordeaux Cedex, France. Phone: (33) 556.795.910. Fax: (33) 556.796.018. E-mail:
francis.megraud{at}chu-aquitaine.fr.
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