scholarly journals Streptococcus pyogenes Pharyngeal Isolates with Reduced Susceptibility to Ciprofloxacin in Spain: Mechanisms of Resistance and Clonal Diversity

2005 ◽  
Vol 49 (1) ◽  
pp. 418-420 ◽  
Author(s):  
Sebastián Albertí ◽  
Guadalupe Cortés ◽  
Cesar García-Rey ◽  
Carmen Rubio ◽  
Fernando Baquero ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Streptococcus Pyogenes ◽  
Point Mutations ◽  
Clonal Diversity ◽  
Gene Sequences ◽  
Mechanisms Of Resistance ◽  
Topoisomerase Iv ◽  
Subunit C ◽  
Pulsed Field ◽  
Ciprofloxacin Resistance

ABSTRACT A survey of emm gene sequences and an analysis of the pulsed-field electrophoretic profiles of 30 Streptococcus pyogenes isolates with reduced susceptibilities to ciprofloxacin detected the prevalence of isolates with emm type 6 and considerable genetic diversity among isolates. The mechanism of ciprofloxacin resistance in these isolates was based on point mutations in topoisomerase IV subunit C encoded by parC, mainly replacement of serine-79 by alanine.

scholarly journals Streptococcus pneumoniae Isolates with Reduced Susceptibility to Ciprofloxacin in Spain: Clonal Diversity and Appearance of Ciprofloxacin-Resistant Epidemic Clones

2001 ◽  
Vol 45 (10) ◽  
pp. 2955-2957 ◽  
Author(s):  
Luis Alou ◽  
Mario Ramirez ◽  
César Garcı́a-Rey ◽  
José Prieto ◽  
Hermı́nia de Lencastre
Keyword(s):  
Genetic Diversity ◽  
Streptococcus Pneumoniae ◽  
Clonal Diversity ◽  
Close Relation ◽  
Pulsed Field

ABSTRACT Analysis of the pulsed-field gel electrophoretic profiles of 82 pneumococcal isolates with reduced susceptibility to ciprofloxacin (RSC) and of 90 co-occurring susceptible isolates indicates a considerable genetic diversity among isolates with RCS and points to a close relation between the two groups. This finding suggests that pneumococci with RCS emerge through independent mutational events.

scholarly journals Prevalence and Mechanisms of Macrolide Resistance in Streptococcus pyogenes in Santiago, Chile

2001 ◽  
Vol 45 (1) ◽  
pp. 339-341 ◽  
Author(s):  
E. L. Palavecino ◽  
I. Riedel ◽  
X. Berrios ◽  
S. Bajaksouzian ◽  
D. Johnson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Streptococcus Pyogenes ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Macrolide Resistance ◽  
Clinical Isolates ◽  
Pulsed Field

ABSTRACT Thirty-two macrolide-resistant Streptococcus pyogenesisolates were found among 594 clinical isolates collected from 1990 to 1998 in Santiago, Chile, for an overall prevalence of 7.2%. Among the 32 resistant isolates, 28 (87.5%) presented the M phenotype and 4 (12.5%) presented the MLSB phenotype. Serotyping and pulsed-field gel electrophoresis analysis showed genetic diversity among the resistant isolates.

scholarly journals Knock-in and precise nucleotide substitution using near-PAMless engineered Cas9 variants in Dictyostelium discoideum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuu Asano ◽  
Kensuke Yamashita ◽  
Aoi Hasegawa ◽  
Takanori Ogasawara ◽  
Hoshie Iriki ◽  
...  
Keyword(s):  
Genome Editing ◽  
Dictyostelium Discoideum ◽  
Streptococcus Pyogenes ◽  
Nucleotide Substitution ◽  
Point Mutations ◽  
Targeted Mutagenesis ◽  
Single Amino Acid ◽  
Specific Gene ◽  
Knock Out ◽  
Protospacer Adjacent Motif

AbstractThe powerful genome editing tool Streptococcus pyogenes Cas9 (SpCas9) requires the trinucleotide NGG as a protospacer adjacent motif (PAM). The PAM requirement is limitation for precise genome editing such as single amino-acid substitutions and knock-ins at specific genomic loci since it occurs in narrow editing window. Recently, SpCas9 variants (i.e., xCas9 3.7, SpCas9-NG, and SpRY) were developed that recognise the NG dinucleotide or almost any other PAM sequences in human cell lines. In this study, we evaluated these variants in Dictyostelium discoideum. In the context of targeted mutagenesis at an NG PAM site, we found that SpCas9-NG and SpRY were more efficient than xCas9 3.7. In the context of NA, NT, NG, and NC PAM sites, the editing efficiency of SpRY was approximately 60% at NR (R = A and G) but less than 22% at NY (Y = T and C). We successfully used SpRY to generate knock-ins at specific gene loci using donor DNA flanked by 60 bp homology arms. In addition, we achieved point mutations with efficiencies as high as 97.7%. This work provides tools that will significantly expand the gene loci that can be targeted for knock-out, knock-in, and precise point mutation in D. discoideum.

ATP synthase subunit c/III/9 gene sequences as a tool for interkingdom and metaphytes molecular phylogenies

1992 ◽  
Vol 34 (4) ◽  
pp. 292-303 ◽  
Author(s):  
Herv� Recipon ◽  
Roland Perasso ◽  
Andr� Adoutte ◽  
Francis Quetier
Keyword(s):  
Atp Synthase ◽  
Gene Sequences ◽  
Subunit C ◽  
Molecular Phylogenies

scholarly journals Genetic diversity and selection of genotypes to enhance Zn and Fe content in common bean

2010 ◽  
Vol 90 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Z I Talukder ◽  
E Anderson ◽  
P N Miklas ◽  
M W Blair ◽  
J Osorno ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Common Bean ◽  
Allelic Variation ◽  
Gene Pools ◽  
Gene Sequences ◽  
Mineral Contents ◽  
Discriminatory Ability ◽  
Fe Content ◽  
Mapping Populations ◽  
Selection Of

Common bean (Phaseolus vulgaris L.) is an important source of dietary protein and minerals worldwide. Genes conditioning variability for mineral contents are not clearly understood. Our ultimate goal is to identify genes conditioning genetic variation for Zn and Fe content. To establish mapping populations for this objective, we tested mineral content of 29 common bean genotypes. Chemical analyses revealed significant genetic variability for seed Zn and Fe contents among the genotypes. Genetic diversity was evaluated with 49 primer pairs, of which 23 were simple sequence repeats (SSR), 16 were developed from tentative consensus (TC) sequences, and 10 were generated from common bean NBS-LRR gene sequences. The discriminatory ability of molecular markers for identifying allelic variation among genotypes was estimated by polymorphism information content (PIC) and the genetic diversity was measured from genetic similarities between genotypes. Primers developed from NBS-LRR gene sequences were highly polymorphic in both PIC values and number of alleles (0.82 and 5.3), followed by SSRs (0.56 and 3.0), and markers developed from TC (0.39 and 2.0). genetic similarity values between genotypes ranged from 14.0 (JaloEEP558 and DOR364) to 91.4 (MIB152 and MIB465). Cluster analysis clearly discriminated the genotypes into Mesoamerican and Andean gene pools. Common bean genotypes were selected to include in crossing to enhance seed Zn and Fe content based on genetic diversity and seed mineral contents of the genotypes. Key words: Common bean, genetic diversity, mineral nutrients, breeding

scholarly journals Mechanisms of quinolone resistance and implications for human and animal health

2010 ◽  
Vol 64 (3-4) ◽  
pp. 277-285
Author(s):  
Maja Velhner ◽  
Gordana Kozoderovic ◽  
Zora Jelesic ◽  
Igor Stojanov ◽  
Radomir Ratajac ◽  
...  
Keyword(s):  
Veterinary Medicine ◽  
Antimicrobial Resistance ◽  
Protein Interactions ◽  
Bacterial Infections ◽  
Animal Health ◽  
Point Mutations ◽  
Inhibitory Effect ◽  
Quinolone Resistance ◽  
Topoisomerase Iv ◽  
Target Enzyme

Quinolone antibiotics have been widely used in human and veterinary medicine. This has caused the development of resistance and difficulties in the treatment of complicated bacterial infections in humans. The resistance to quinolones develops due to chromosome mutations and it can also be transferred by plasmids. The target enzyme for quinolones in Gram-negative bacteria is Gyrasa A, while the target enzyme in Grampositive bacteria is mostly topoisomerase IV. Gyrase A consists of two subunits encoded by genes gyrA and gyrB. The function of the enzyme is to introduce negative super coiling in DNA and therefore is essential for the replication of bacteria. Quinolone resistance develops if point mutations at 83 and/or 87 codon are introduced on gyrA. Establishing a minimal inhibitory concentration (MIC) to this group of antimicrobials will reveal possible mutations. Recently it was discovered that quinolone resistance is transmittable by plasmid termed PMQR (plasmid mediated quinolone resistance). The target gene marked qnr encodes a pentapeptide repeat family protein. Pentapeptide repeats form sheets, involved in protein-protein interactions. Qnr protein binds to GyrA protecting the enzyme from the inhibitory effect of ciprofloxacin. The distribution of qnr related resistance is higher in humans than in animals. In poultry, however, this type of resistance is present more than in other animals. Plasmid mediated resistance contributes to the faster spread of quinolone resistance. Proper food handling will significantly contribute to decreasing the risk from infection to which people are exposed. In medical and veterinary laboratories antimicrobial resistance monitoring in clinical and environmental isolates is advised. Since correlation between antibiotics application and antimicrobial resistance is often suggested, antimicrobial use must be under strict control of the authorities both in human and in veterinary medicine. .

scholarly journals Prevalence And Characterization Of Plasmid-Mediated Quinolone Resistance In Various Aquatic Sources

2021 ◽  
Author(s):  
Farhan Yusuf ◽  
Kimberley Gilbride
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Antibiotic Resistance Genes ◽  
Quinolone Resistance ◽  
Resistant Bacteria ◽  
Rrna Gene ◽  
Environmental Isolates ◽  
Topoisomerase Iv ◽  
Phenotypic Resistance ◽  
Ciprofloxacin Resistance

Bacterial isolates found in aquatic ecosystems often carry antibiotic resistance genes (ARGs). These ARGs are often found on plasmids and transposons, which allows them to be proliferate throughout bacterial communities via horizontal gene transfer (HGT) causing dissemination of multidrug resistance. The increase in antibiotic resistance has raised concerns about the ability to continue to use these drugs to fight infectious diseases. Novel synthetic antibiotics like ciprofloxacin that are not naturally found in the environment were developed to prevent resistances. However, ciprofloxacin resistance has occurred through chromosomal gene mutations of type 2 topoisomerases or by the acquisition of plasmid-mediated quinolone resistances (PMQR). A particular PMQR, qnr genes, encoding for pentapeptide repeat proteins that confer low levels of quinolone resistance and protect DNA gyrase and topoisomerase IV from antibacterial activity. These qnr genes have been identified globally in both clinical and environmental isolates. The aim of this study was to determine the prevalence of ciprofloxacin-resistant bacteria in aquatic environments in the Greater Toronto Area and the potential dissemination of ciprofloxacin resistance. With the selective pressure of ciprofloxacin, we hypothesize that ciprofloxacin-resistant bacteria (CipR) in the environment may carry PMQR mechanisms while the sensitive population (CipS) would not carry PMQR genes. Isolates were tested for resistance to an additional 12 different antibiotics and identified using Sanger sequencing PCR products of the 16S rRNA gene. To determine which genes are responsible for ciprofloxacin resistance, multiplex PCR of associated qnr genes, qnrA, qnrB, and qnrS, was carried out on 202 environmental isolates. Our data demonstrate a similar prevalence of qnr genes was found in CipR (19%) and CipS (14%) populations suggesting that the presence of these genes was not necessarily correlated with the phenotypic resistance to the antibiotic. Furthermore, ciprofloxacinresistant bacteria were found in all locations at similar frequencies suggesting that resistance genes are widespread and could possibly arise through HGT events. Overall, determining the underlying cause and prevalence of ciprofloxacin resistance could help re-establish the effectiveness of these antimicrobial compounds.

scholarly journals Genetic Dissimilarity in Conyza sumatrensis Revealed by Simple Sequence Repeat (SSR) Markers

2020 ◽  
Vol 38 ◽  
Author(s):  
T. SCHNEIDER ◽  
M.A. RIZZARDI ◽  
S.P. BRAMMER ◽  
S.M. SCHEFFER-BASSO ◽  
A.L. NUNES
Keyword(s):  
Genetic Diversity ◽  
Management Strategies ◽  
Rapid Evolution ◽  
Jaccard Coefficient ◽  
Mechanisms Of Resistance ◽  
High Genetic Diversity ◽  
Resistance To Herbicides ◽  
Geographic Regions ◽  
Genetic Dissimilarity ◽  
Simple Sequence

ABSTRACT: In view of the rapid evolution of Conyza sumatrensis populations resistant to glyphosate, it is necessary to understand the genetic diversity aimed to improve strategies for managing this weed. We investigated the genetic dissimilarity among 15 biotypes of C. sumatrensis from different geographic regions using microsatellite loci. The biotypes, were cultivated in a greenhouse to obtain vegetal material for DNA extraction. Nineteen microsatellite markers (SSR), were developed for C. sumatrensis biotypes. The genetic dissimilarity was estimated by the Jaccard coefficient (JC) and the biotypes grouped by the UPGMA method. The results demonstrated a high dissimilarity (JC = 7.14 to 82.62) of the analyzed material, with the biotypes forming five groups, being one group formed just by the susceptible biotype and in the others grouped by biotypes from distinct locations in the same group The high genetic diversity of C. sumatrensis indicates that the biotypes may show different responses to different management strategies, and that the mechanisms of resistance to herbicides and characteristics of evolution of populations due to adaptability may be some of the factors involved in the genetic variability of the species.

scholarly journals Genetic interplay between type II topoisomerase enzymes and chromosomal ccdAB toxin-antitoxin in E. coli

2021 ◽  
Author(s):  
Jay Wook Joong Kim ◽  
Vincent Blay ◽  
Portia Mira ◽  
Miriam Barlow ◽  
Manel Camps
Keyword(s):  
Public Health ◽  
Genetic Markers ◽  
Indirect Effect ◽  
Quinolone Resistance ◽  
Type Ii ◽  
Topoisomerase Iv ◽  
E Coli ◽  
Resistance Evolution ◽  
Selective Pressures ◽  
Ciprofloxacin Resistance

Fluoroquinolones are one of the most widely used class of antibiotics. They target two type II topoisomerase enzymes: gyrase and topoisomerase IV. Resistance to these drugs, which is largely caused by mutations in their target enzymes, is on the rise and becoming a serious public health risk. In this work, we analyze the sequences of 352 extraintestinal E. coli clinical isolates to gain insights into the selective pressures shaping the type II topoisomerase mutation landscape in E. coli. We identify both Quinolone Resistance-Determining Region (QRDR) and non-QRDR mutations, outline their mutation trajectories, and show that they are likely driven by different selective pressures. We confirm that ciprofloxacin resistance is specifically and strongly associated with QRDR mutations. By contrast, non-QRDR mutations are associated with the presence of the chromosomal version of ccdAB, a toxin-antitoxin operon, where the toxin CcdB is known to target gyrase. We also find that ccdAB and the evolution of QRDR mutation trajectories are partially incompatible. Finally, we identify partial deletions in CcdB and additional mutations that likely facilitate the compatibility between the presence of the ccdAB operon and QRDR mutations. These "permissive" mutations are all found in ParC (a topoisomerase IV subunit). This, and the fact that CcdB-selected mutations frequently map to topoisomerase IV, strongly suggests that this enzyme (in addition to gyrase) is likely a target for the toxin CcdB in E. coli, although an indirect effect on global supercoiling cannot be excluded. This work opens the door for the use of the presence of ccdB and of the proposed permissive mutations in the genome as genetic markers to assess the risk of quinolone resistance evolution and implies that certain strains may be genetically more refractory to evolving quinolone resistance through mutations in target enzymes.

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