scholarly journals Pathophysiology of Antibiotic Resistance: Clarithromycin

2000 ◽  
Vol 14 (10) ◽  
pp. 891-894 ◽  
Author(s):  
Diane E Taylor
Keyword(s):  
Inhibitory Concentration ◽  
Natural Transformation ◽  
Rrna Genes ◽  
23S Rrna ◽  
Cross Resistance ◽  
In Vitro Mutagenesis ◽  
Clarithromycin Resistance ◽  
23S Rrna Genes ◽  
H Pylori

Resistance ofHelicobacter pylorito antibiotics ranges from 3% to 10% and may exceed these levels in some countries. The pathophysiology of clarithromycin resistance is reviewed, including the mode of action by which the antibiotic inhibits protein synthesis and the mechanism of resistance, which involves a mutation at position 2142 or 2143 in the V loop domain of the 23S rRNA genes. Mutations of A2142G confer a higher minimum inhibitory concentration than mutations of A2143G. The former demonstrate cross-resistance to macrolide, lincosamide and streptogramin antibiotics, whereas the latter are susceptible to streptogramin B. In vitro mutagenesis combined with natural transformation were used to create several types of clarithromycin-resistant mutants.H pyloristrains with A2142G and A2143G mutations had a higher growth rate than those with A2142C, A2143 or A2142T mutations. Data from this study indicate why clarithromycin-resistant clinical isolates ofH pyloriare more likely to have A2142G or A2143G mutations and only occasionally A2142C mutations.

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 Genotypic and Phenotypic Resistance to Clarithromycin in Helicobacter pylori Strains

2020 ◽  
Vol 9 (6) ◽  
pp. 1930
Author(s):  
Eun Jeong Gong ◽  
Ji Yong Ahn ◽  
Jung Mogg Kim ◽  
Sun Mi Lee ◽  
Hee Kyong Na ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Antimicrobial Resistance ◽  
Rrna Genes ◽  
23S Rrna ◽  
Dilution Method ◽  
Phenotypic Resistance ◽  
Clarithromycin Resistance ◽  
Resistant Phenotype ◽  
23S Rrna Genes ◽  
H Pylori

Background: The increasing prevalence of antimicrobial resistance, together with the lack of novel treatment options, negatively affects successful eradication of Helicobacter pylori. The aim of this study was to investigate genetic mutations in the 23S rRNA genes, which is associated with clarithromycin resistance, and to determine the clinical impact of genotype on phenotypic antimicrobial resistance. Methods: A total of 46 H. pylori strains were obtained from 13 patients, before and after unsuccessful eradication with clarithromycin-based triple therapy. The phenotypic resistance of each H. pylori strain was determined by minimum inhibitory concentration against clarithromycin using the serial two-fold agar dilution method. The genomic sequences of 23S rRNA genes were identified through next-generation sequencing, and nucleotide variants were determined based on comparison with genome sequences of the reference strain H. pylori 26695. Results: Clarithromycin resistance was found in 9 of 13 subjects before treatment and all subjects after unsuccessful eradication. Whole-genome sequencing of the 23S rRNA genes detected 42 mutations on 40 nonidentical loci, including 2147A>G (formerly 2143A>G) and 2146A>G (formerly 2142A>G). All strains with clarithromycin-resistant phenotype had either 2147A>G or 2146A>G mutation. When comparing genotype and phenotype for clarithromycin resistance, there was a significant association between 2147A>G mutation and clarithromycin-resistant phenotype. Conclusions: All clarithromycin-resistant strains had either 2146A>G or 2147A>G mutation, suggesting that tests targeting these two mutations may be enough for the prediction of clarithromycin resistance in this population.

scholarly journals cfr(B), cfr(C), and a New cfr-Like Gene, cfr(E), in Clostridium difficile Strains Recovered across Latin America

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
Vanja Stojković ◽  
María Fernanda Ulate ◽  
Fanny Hidalgo-Villeda ◽  
Emmanuel Aguilar ◽  
Camilo Monge-Cascante ◽  
...  
Keyword(s):  
Latin America ◽  
Clostridium Difficile ◽  
Ribosomal Proteins ◽  
Rrna Genes ◽  
23S Rrna ◽  
Cross Resistance ◽  
Content Type ◽  
Integrative And Conjugative Elements ◽  
Genes Encoding

ABSTRACT Cfr is a radical S-adenosyl-l-methionine (SAM) enzyme that confers cross-resistance to antibiotics targeting the 23S rRNA through hypermethylation of nucleotide A2503. Three cfr-like genes implicated in antibiotic resistance have been described, two of which, cfr(B) and cfr(C), have been sporadically detected in Clostridium difficile. However, the methylase activity of Cfr(C) has not been confirmed. We found cfr(B), cfr(C), and a cfr-like gene that shows only 51 to 58% protein sequence identity to Cfr and Cfr-like enzymes in clinical C. difficile isolates recovered across nearly a decade in Mexico, Honduras, Costa Rica, and Chile. This new resistance gene was termed cfr(E). In agreement with the anticipated function of the cfr-like genes detected, all isolates exhibited high MIC values for several ribosome-targeting antibiotics. In addition, in vitro assays confirmed that Cfr(C) and Cfr(E) methylate Escherichia coli and, to a lesser extent, C. difficile 23S rRNA fragments at the expected positions. The analyzed isolates do not have mutations in 23S rRNA genes or genes encoding the ribosomal proteins L3 and L4 and lack poxtA, optrA, and pleuromutilin resistance genes. Moreover, these cfr-like genes were found in Tn6218-like transposons or integrative and conjugative elements (ICE) that could facilitate their transfer. These results indicate selection of potentially mobile cfr-like genes in C. difficile from Latin America and provide the first assessment of the methylation activity of Cfr(C) and Cfr(E), which belong to a cluster of Cfr-like proteins that does not include the functionally characterized enzymes Cfr, Cfr(B), and Cfr(D).

scholarly journals The Absence of Intervening Sequences in 23S rRNA Genes of Campylobacter coli Isolates from Turkeys Is a Unique Attribute of a Cluster of Related Strains Which Also Lack Resistance to Erythromycin

2006 ◽  
Vol 73 (4) ◽  
pp. 1208-1214 ◽  
Author(s):  
Kamfai Chan ◽  
William G. Miller ◽  
Robert E. Mandrell ◽  
Sophia Kathariou
Keyword(s):  
Natural Transformation ◽  
Rrna Genes ◽  
23S Rrna ◽  
Rrna Gene ◽  
Campylobacter Coli ◽  
Erythromycin Resistance ◽  
Intervening Sequences ◽  
23S Rrna Gene ◽  
23S Rrna Genes ◽  
Sequence Types

ABSTRACT Certain Campylobacter strains harbor a transcribed intervening sequence (IVS) in their 23S rRNA genes. Following transcription, the IVS is excised, leading to fragmentation of the 23S rRNA. The origin and possible functions of the IVS are unknown. Furthermore, the distribution of IVS-harboring strains within Campylobacter populations is poorly understood. In this study, 104 strains of Campylobacter coli from turkeys, representing 27 different multilocus sequence typing-based sequence types (STs), were characterized in terms of IVS content and erythromycin susceptibility. Sixty-nine strains harbored IVSs in all three 23S rRNA genes, whereas the other 35 strains lacked IVSs from at least one of the genes. The STs of the latter strains belonged to an unusual cluster of C. coli STs (cluster II), earlier found primarily in turkey strains and characterized by the presence of the C. jejuni aspA103 allele. The majority (66/69) of strains harboring IVSs in all three 23S rRNA genes were resistant to erythromycin, whereas none of the 35 strains with at least one IVS-free 23S rRNA gene were resistant. Cluster II strains could be transformed to erythromycin resistance with genomic DNA from C. coli that harbored IVS and the A2075G transition in the 23S rRNA gene, associated with resistance to erythromycin in Campylobacter. Erythromycin-resistant transformants harbored both the A2075 transition and IVS. The findings suggest that the absence of IVS in C. coli from turkeys is characteristic of a unique clonal group of erythromycin-susceptible strains and that IVS can be acquired by these strains via natural transformation to erythromycin resistance.

scholarly journals Recombination Proficiency Influences Frequency and Locus of Mutational Resistance to Linezolid in Enterococcus faecalis

2003 ◽  
Vol 47 (10) ◽  
pp. 3318-3320 ◽  
Author(s):  
Michael Lobritz ◽  
Rebecca Hutton-Thomas ◽  
Steve Marshall ◽  
Louis B. Rice
Keyword(s):  
Enterococcus Faecalis ◽  
Single Copy ◽  
Rrna Genes ◽  
23S Rrna ◽  
Linezolid Resistance ◽  
23S Rrna Genes

ABSTRACT In vitro linezolid resistance was selected at a higher frequency in Enterococcus faecalis JH2-2 than in recombination-deficient E. faecalis UV202. Resistance in JH2-2 was related to accumulated G2576T mutations in 23S rRNA genes, with the least resistance conferred by mutations in two of four copies. UV202 resistance was associated with a G2505A mutation present in a single copy in mutants with different MICs.

scholarly journals Development of a Microelectronic Chip Array for High-Throughput Genotyping of Helicobacter Species and Screening for Antimicrobial Resistance

2005 ◽  
Vol 10 (3) ◽  
pp. 235-245 ◽  
Author(s):  
James Z. Xing ◽  
Chris Clarke ◽  
Lijun Zhu ◽  
Stephan Gabos
Keyword(s):  
Antimicrobial Resistance ◽  
16S Rrna ◽  
Tetracycline Resistance ◽  
Rrna Genes ◽  
23S Rrna ◽  
Rrna Gene ◽  
Nucleotide Polymorphisms ◽  
23S Rrna Gene ◽  
23S Rrna Genes ◽  
H Pylori

A microelectronic array assay was developed to specifically genotype Helicobacter pylori versus Helicobacter heilmannii and to determine antimicrobial resistance. Helicobacter 16S rRNA and 23S rRNA genes were specifically generated with Helicobacter genus-specific primers, respectively. The single-nucleotide polymorphisms (SNPs) in 16S rRNA, 268T specific in the H. pylori sequence, and 263A specific in H. heilmannii were used as molecular markers for identification of H. pylori and H. heilmannii, respectively. A triple-base-pair resistant mutation, AGA965-967TTC in 16S rRNA, is known to be responsible for H. pylori tetracycline resistance and was detected to identify resistant strains. H. pylori macrolide resistance was determined by the identification of 3 defined mutations in the 23S rRNA gene using the same method. The assay could be directly used to detect H. pylori in feces. The assay performs multiple determinations, including identification of Helicobacter species and antibiotic resistances, on the same microelectronic platform and is highly amenable to the development of other DNA-based assays.

scholarly journals Site-Specific Mutations in the 23S rRNA Gene ofHelicobacter pylori Confer Two Types of Resistance to Macrolide-Lincosamide-Streptogramin B Antibiotics

1998 ◽  
Vol 42 (8) ◽  
pp. 1952-1958 ◽  
Author(s):  
Ge Wang ◽  
Diane E. Taylor
Keyword(s):  
Point Mutations ◽  
Clinical Isolates ◽  
23S Rrna ◽  
Cross Resistance ◽  
Rrna Gene ◽  
Type I ◽  
Type Ii ◽  
Clarithromycin Resistance ◽  
23S Rrna Gene ◽  
H Pylori

ABSTRACT Clarithromycin resistance in Helicobacter pylori is mainly due to A-to-G mutations within the peptidyltransferase region of the 23S rRNA. In the present study, cross-resistance to macrolide, lincosamide, and streptogramin B (MLS) antibiotics (MLS phenotypes) has been investigated for several clinical isolates of H. pylori. Two major types of MLS resistance were identified and correlated with specific point mutations in the 23S rRNA gene. The A2142G mutation was linked with high-level cross-resistance to all MLS antibiotics (type I), and the A2143G mutation gave rise to an intermediate level of resistance to clarithromycin and clindamycin but no resistance to streptogramin B (type II). In addition, streptogramin A and streptogramin B were demonstrated to have a synergistic effect on both MLS-sensitive and MLS-resistant H. pyloristrains. To further understand the mechanism of MLS resistance inH. pylori, we performed in vitro site-directed mutagenesis (substitution of G, C, or T for A at either position 2142 or 2143 of the 23S rRNA gene). The site-directed point mutations were introduced into a clarithromycin-susceptible strain, H. pylori UA802, by natural transformation followed by characterization of their effects on MLS resistance in an isogenic background. Strains with A-to-G and A-to-C mutations at the same position within the 23S rRNA gene had similar levels of clarithromycin resistance, and this level of resistance was higher than that for strains with the A-to-T mutation. Mutations at position 2142 conferred a higher level of clarithromycin resistance than mutations at position 2143. All mutations at position 2142 conferred cross-resistance to all MLS antibiotics, which corresponds to the type I MLS phenotype, whereas mutations at position 2143 were associated with a type II MLS phenotype with no resistance to streptogramin B. To explain that A-to-G transitions were predominantly observed in clarithromycin-resistant clinical isolates, we propose a possible mechanism by which A-to-G mutations are preferentially produced in H. pylori.

scholarly journals Spontaneous Mutations That Confer Antibiotic Resistance inHelicobacter pylori

2001 ◽  
Vol 45 (3) ◽  
pp. 727-733 ◽  
Author(s):  
Ge Wang ◽  
Trevor J. M. Wilson ◽  
Qin Jiang ◽  
Diane E. Taylor
Keyword(s):  
Mutant Allele ◽  
Rapid Development ◽  
Mutagenic Effect ◽  
Serial Passage ◽  
Sublethal Dose ◽  
23S Rrna ◽  
Rrna Gene ◽  
Spontaneous Mutations ◽  
H Pylori

ABSTRACT In this study, we systematically examined in vitro frequencies and spectra of the spontaneous mutations in Helicobacter pylori that confer resistance to clarithromycin (Clar), metronidazole (Mtzr), amoxicillin (Amxr), ciprofloxacin (Cipr), and rifampin (Rifr). The mutation rate of Rifror Cipr determined in a fluctuation assay is 1 × 10−8 to 2 × 10−8 per cell per division. In contrast, the mutation rates of Clar, Mtzr, and Amxr are much lower (<10−9). However, Mtzr mutants could be readily selected in vitro by using the serial passage method, suggesting that the mutagenic effect and selective effect of a sublethal dose of metronidazole contribute to the rapid development of Mtzr. Analysis of spontaneous Rifr, Clar, and Cipr mutants confirmed previous results indicating that mutations within therpoB gene, the 23S rRNA gene, and thegyrA gene, respectively, are responsible; also, several new mutant alleles were identified. Mtzrmutants resulted most frequently, but not always, from mutations in the rdxA gene. DNA fragments containing each mutant allele could readily transform susceptibleH. pylori strains to resistance, confirming that each mutant allele is responsible for the resistance phenotype.

Demonstration of the absence of intervening sequences within 23S rRNA genes fromCampylobacter lari

2009 ◽  
Vol 49 (4) ◽  
pp. 386-394 ◽  
Author(s):  
Akihiro Tazumi ◽  
Yuki Kakinuma ◽  
John E. Moore ◽  
Cherie B. Millar ◽  
Ikue Taneike ◽  
...  
Keyword(s):  
Rrna Genes ◽  
23S Rrna ◽  
Intervening Sequences ◽  
23S Rrna Genes
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