scholarly journals Association of Metronidazole Resistance and Natural Competence in Helicobacter pylori

2002 ◽  
Vol 46 (5) ◽  
pp. 1564-1567 ◽  
Author(s):  
Yu-Ching Yeh ◽  
Kai-Chin Chang ◽  
Jyh-Chin Yang ◽  
Chi-Tai Fang ◽  
Jin-Town Wang
Keyword(s):  
Helicobacter Pylori ◽  
Natural Transformation ◽  
23S Rrna ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Rrna Gene ◽  
Natural Competence ◽  
Metronidazole Resistance ◽  
23S Rrna Gene ◽  
Agar Dilution

ABSTRACT To study whether the capability of horizontal DNA transfer is associated with metronidazole resistance in Helicobacter pylori, a total of 81 clinical isolates were tested for MICs of metronidazole (MTZ). The MIC assays were performed by using the E-test and reconfirmed by the agar dilution method. Natural competence assays were performed by transferring a chloramphenicol acetyltransferase cassette and a 23S rRNA gene from a clarithromycin-resistant strain (with an A-to-G mutation at nucleotide 2143) by using natural transformation. Of the 81 isolates, 65 (80.2%) were naturally competent while 16 were not. Among the 65 naturally competent strains, 39 (60%) were highly resistant to MTZ (MICs, >32 μg/ml) while only 2 of 16 (12.5%) noncompetent strains were highly MTZ resistant (P, <0.001). Therefore, there is an association between natural competence and MTZ resistance.

scholarly journals New Site of Modification of 23S rRNA Associated with Clarithromycin Resistance of Helicobacter pylori Clinical Isolates

2002 ◽  
Vol 46 (12) ◽  
pp. 3765-3769 ◽  
Author(s):  
Carla Fontana ◽  
Marco Favaro ◽  
Silvia Minelli ◽  
Anna Angela Criscuolo ◽  
Antonio Pietroiusti ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
23S Rrna ◽  
Dilution Method ◽  
Rrna Gene ◽  
Functional Sites ◽  
Biopsy Specimens ◽  
Clarithromycin Resistance ◽  
Pcr Product ◽  
23S Rrna Gene ◽  
H Pylori

ABSTRACT Resistance of Helicobacter pylori to clarithromycin occurs with a prevalence ranging from 0 to 15%. This has an important clinical impact on dual and triple therapies, in which clarithromycin seems to be the better choice to achieve H. pylori eradication. In order to evaluate the possibility of new mechanisms of clarithromycin resistance, a PCR assay that amplified a portion of 23S rRNA from H. pylori isolates was used. Gastric tissue biopsy specimens from 230 consecutive patients were cultured for H. pylori isolation. Eighty-six gastric biopsy specimens yielded H. pylori-positive results, and among these 12 isolates were clarithromycin resistant. The latter were studied to detect mutations in the 23S rRNA gene. Sequence analysis of the 1,143-bp PCR product (portion of the 23S rRNA gene) did not reveal mutation such as that described at position 2142 to 2143. On the contrary, our findings show, for seven isolates, a T-to-C transition at position 2717. This mutation conferred a low level of resistance, equivalent to the MIC for the isolates, selected using the E-test as well as using the agar dilution method: 1 μg/ml. Moreover, T2717C transition is located in a highly conserved region of the 23S RNA associated with functional sites: domain VI. This fact has a strong effect on the secondary structure of the 23S RNA and on its interaction with macrolide. Mutation at position 2717 also generated an HhaI restriction site; therefore, restriction analysis of the PCR product also permits a rapid detection of resistant isolates.

scholarly journals PCR Using 3′-Mismatched Primers To Detect A2142C Mutation in 23S rRNA Conferring Resistance to Clarithromycin in Helicobacter pylori Clinical Isolates

2000 ◽  
Vol 38 (2) ◽  
pp. 923-925 ◽  
Author(s):  
Teresa Alarcón ◽  
Diego Domingo ◽  
Nuria Prieto ◽  
Manuel López-Brea
Keyword(s):  
Helicobacter Pylori ◽  
Restriction Fragment Length Polymorphism ◽  
Length Polymorphism ◽  
Fragment Length Polymorphism ◽  
23S Rrna ◽  
Rrna Gene ◽  
Specific Primer ◽  
23S Rrna Gene ◽  
Agar Dilution ◽  
Restriction Fragment Length

Twenty-five clarithromycin-resistant Helicobacter pylori strains (selected by agar dilution) were studied to detect A2142G and A2143G mutations in the 23S rRNA gene by a PCR-restriction fragment length polymorphism method and an A2142C mutation by PCR using a 3′-mismatched specific primer. A 700-bp amplified fragment was obtained by the mismatched PCR only in strains without an A2142G or A2143G mutation, indicating that those strains had the A2142C mutation.

scholarly journals Cloning and sequence analysis of two copies of a 23S rRNA gene from Helicobacter pylori and association of clarithromycin resistance with 23S rRNA mutations.

1997 ◽  
Vol 41 (12) ◽  
pp. 2621-2628 ◽  
Author(s):  
D E Taylor ◽  
Z Ge ◽  
D Purych ◽  
T Lo ◽  
K Hiratsuka
Keyword(s):  
Helicobacter Pylori ◽  
Natural Transformation ◽  
Rrna Genes ◽  
23S Rrna ◽  
Rrna Gene ◽  
Donor Strain ◽  
Clarithromycin Resistance ◽  
23S Rrna Gene ◽  
23S Rrna Genes ◽  
H Pylori

In this study, two identical copies of a 23S-5S gene cluster, which are separately situated within the Helicobacter pylori UA802 chromosome, were cloned and sequenced. Comparison of the DNA sequence of the H. pylori 23S rRNA gene with known sequences of other bacterial 23S rRNA genes indicated that the H. pylori UA802 23S rRNA genes are closely related to those of Campylobacter spp. and therefore belong in the proposed Proteobacteria subdivision. The 5'-terminal nucleotide T or A of the 23S rRNA is close to a Pribnow box which could be a -10 region of the transcription promoter for the 23S rRNA gene, suggesting that a posttranscriptional process is likely not involved in the maturation of the H. pylori 23S rRNA. Clinical isolates of H. pylori resistant to clarithromycin were examined by using natural transformation and pulsed-field gel electrophoresis. Cross-resistance to clarithromycin and erythromycin, which was transferred by natural transformation from the Cla(r) Ery(r) donor strain H. pylori E to the Cla(s) Ery(s) recipient strain H. pylori UA802, was associated with an single A-to-G transition mutation at position 2142 of both copies of the 23S rRNA in UA802 Cla(r) Ery(r) mutants. The transformation frequency for Cla(r) and Ery(r) was found to be approximately 2 x 10(-6) transformants per viable cell, and the MICs of both clarithromycin and erythromycin for the Cla(r) Ery(r) mutants were equal to those for the donor isolate. Our results confirmed the previous findings that mutations at positions 2142 and 2143 of the H. pylori 23S rRNA gene are responsible for clarithromycin resistance and suggest that acquisition of clarithromycin resistance in H. pylori could also result from horizontal transfer.

scholarly journals Detection of Clarithromycin-Resistant Helicobacter pylori Strains by a Preferential Homoduplex Formation Assay

2000 ◽  
Vol 38 (1) ◽  
pp. 210-214
Author(s):  
Shin Maeda ◽  
Haruhiko Yoshida ◽  
Hironari Matsunaga ◽  
Keiji Ogura ◽  
Osamu Kawamata ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Point Mutations ◽  
23S Rrna ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Wild Type ◽  
Urease Test ◽  
Agar Dilution ◽  
Type Gene ◽  
H Pylori

ABSTRACT It has been shown that resistance to clarithromycin, a major cause of failure in Helicobacter pylori eradication therapy, is associated with point mutations in the 23S rRNA gene. We sought to apply the preferential homoduplex formation assay (PHFA), a novel technique for the efficient detection of point mutations, to detection of the mutations. PHFA was performed on streptavidin-coated microtiter plates with biotin- and dinitrophenyl-labeled amplicons to detect the wild-type gene or each mutant gene. DNA samples were extracted from gastric juice specimens of 412 patients with H. pylori infection and were applied to the assay. The detection threshold of PHFA was as few as 10 gene copies. The sensitivity of PHFA for the detection of H. pylori infection was higher than those of culture and the rapid urease test. A total of 337 (81.8%) samples had the wild-type gene, 38 (9.2%) had the A2144G mutation, and 37 (9.0%) contained both the wild type and a mutation (A2144G in 30 samples, A2143G in 5 samples, and A2143G plus A2144G in 2 samples). About half the strains isolated from patients with mixed infection were susceptible by the agar dilution method (MIC, <0.1 mg/liter). Therefore, PHFA can detect clarithromycin-resistant H. pylori strains, even in patients with mixed infections with the wild type, that are not detectable by the agar dilution method.

Identification of a 23S rRNA Gene Mutation in Clarithromycin-Resistant Helicobacter pylori

Helicobacter ◽  
1996 ◽  
Vol 1 (4) ◽  
pp. 227-228 ◽  
Author(s):  
Gregory G. Stone ◽  
Dee Shortridge ◽  
Robert K. Flamm ◽  
James Versalovic ◽  
Jill Beyer ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Gene Mutation ◽  
23S Rrna ◽  
Rrna Gene ◽  
23S Rrna Gene

scholarly journals Genotypic Characterization of Clarithromycin-Resistant and -Susceptible Helicobacter pylori Strains from the Same Patient Demonstrates Existence of Two Unrelated Isolates

1998 ◽  
Vol 36 (9) ◽  
pp. 2730-2731 ◽  
Author(s):  
Ge Wang ◽  
Qin Jiang ◽  
Diane E. Taylor
Keyword(s):  
Helicobacter Pylori ◽  
Gel Electrophoresis ◽  
Genomic Dna ◽  
Pulsed Field Gel Electrophoresis ◽  
23S Rrna ◽  
Rrna Gene ◽  
Clarithromycin Resistance ◽  
23S Rrna Gene ◽  
Mode Of Development

Clarithromycin-susceptible and clarithromycin-resistantHelicobacter pylori isolates from the same patient were investigated for the mode of development and mechanism of clarithromycin resistance. The clarithromycin-resistant strain UA1182 harbors homozygous A-to-G mutations at position 2143 in both copies of the 23S rRNA gene and has a phenotype of resistance to clarithromycin and clindamycin but no significant resistance to streptogramin B. Pulsed-field gel electrophoresis patterns of NruI- andNotI-digested genomic DNA from the Clas and Clar isolates demonstrated that they are genetically distinct, suggesting that the development of clarithromycin resistance is not from the mutation of the existing Clas strain but from a completely new strain.

scholarly journals Natural Transformation-Mediated Transfer of Erythromycin Resistance in Campylobacter coli Strains from Turkeys and Swine

2006 ◽  
Vol 72 (2) ◽  
pp. 1316-1321 ◽  
Author(s):  
Joo-Sung Kim ◽  
Donna K. Carver ◽  
Sophia Kathariou
Keyword(s):  
Point Mutation ◽  
Natural Transformation ◽  
23S Rrna ◽  
Rrna Gene ◽  
Campylobacter Coli ◽  
Erythromycin Resistance ◽  
23S Rrna Gene ◽  
High Level ◽  
Human Infections ◽  
Spontaneous Mutants

ABSTRACT Erythromycin resistance in Campylobacter coli from meat animals is frequently encountered and could represent a substantial barrier to antibiotic treatment of human infections. Erythromycin resistance in this organism has been associated with a point mutation (A2075G) in the 23S rRNA gene. However, the mechanisms responsible for possible dissemination of erythromycin resistance in C. coli remain poorly understood. In this study, we investigated transformation-mediated acquisition of erythromycin resistance by genotypically diverse C. coli strains from turkeys and swine, with total genomic DNA from erythromycin-resistant C. coli of either turkey or swine origin used as a donor. Overall, transformation to erythromycin resistance was significantly more frequent in C. coli strains from turkeys than in swine-derived strains (P < 0.01). The frequency of transformation to erythromycin resistance was 10−5 to 10−6 for turkey-derived strains but 10−7 or less for C. coli from swine. Transformants harbored the point mutation A2075G in the 23S rRNA gene, as did the erythromycin-resistant strains used as DNA donors. Erythromycin resistance was stable in transformants following serial transfers in the absence of the antibiotic, and most transformants had high MICs (>256 μg/ml), as did the C. coli donor strains. In contrast to the results obtained with transformation, spontaneous mutants had relatively low erythromycin MICs (32 to 64 μg/ml) and lacked the A2075G mutation in the 23S rRNA gene. These findings suggest that natural transformation has the potential to contribute to the dissemination of high-level resistance to erythromycin among C. coli strains colonizing meat animals.

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