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Green Metal-Based Nanoparticles Synthesized Using Medicinal Plants and Plant Phytochemicals against Multidrug-Resistant Staphylococcus aureus
Published in Richard L. K. Glover, Daniel Nyanganyura, Rofhiwa Bridget Mulaudzi, Maluta Steven Mufamadi, Green Synthesis in Nanomedicine and Human Health, 2021
Abeer Ahmed Qaed Ahmed, Lin Xiao, Tracey Jill Morton McKay, Guang Yang
Many infectious diseases, including S. aureus, became curable due to antibiotics. However, the treatment of S. aureus infections is complex as S. aureus can acquire resistance to antibiotics due to mobile genetic elements (MGEs), the primary way that genetic information can be exchanged by horizontal gene transfer between bacterial cells. MGEs facilitate horizontal genetic exchange, enabling S. aureus to become antibiotic resistant (Partridge et al., 2018). Through this, bacterial cells overcome antibiotics by obtaining pre-existing resistance factors from the bacterial gene pool of bacteria. Mobile genetic elements can move between or within DNA molecules via transposons, gene cassettes/integrons and insertion sequences. Some, such as integrative conjugative elements and plasmids, can be transferred between bacterial cells. S. aureus has MGEs that explain their ability to develop resistance to antibiotics over the years (Fig. 10.3).
Using Genotyping and Molecular Surveillance to Investigate Tuberculosis Transmission
Published in Lloyd N. Friedman, Martin Dedicoat, Peter D. O. Davies, Clinical Tuberculosis, 2020
Sarah Talarico, Laura F. Anderson, Benjamin J. Silk
Genotyping methods for M. tuberculosis can be divided into two main categories: (1) conventional genotyping methods that examine variation affecting a small portion of the M. tuberculosis genome and (2) whole-genome sequencing (WGS), which examines most of the M. tuberculosis genome at the nucleotide level. The three most commonly used conventional genotyping methods are restriction fragment length polymorphism (RFLP), spacer oligonucleotide typing (spoligotyping), and mycobacterial interspersed repetitive units-variable number tandem repeats (MIRU-VNTR). These methods are all based on repetitive DNA sequences found either interspersed throughout the bacterial genome (insertion sequences) or at specific loci. Changes in these repetitive DNA sequences serve as a proxy for genetic diversification that is occurring throughout the entire genome. However, as DNA sequencing technologies have advanced, WGS is replacing the use of conventional genotyping methods for public health purposes to provide direct analysis of phylogenetic relationships at the nucleotide level.
Oncogenic DNA Viruses
Published in Pimentel Enrique, Oncogenes, 2020
Although the molecular mechanisms involved in transformation associated with herpesvirus infection have not been elucidated, small fragments of herpesvirus DNA with no apparent ability to specify a viral polypeptide have transforming capability. This capability is contained in insertion sequence-like structures.34 After integration, such structures could induce alterations in regulatory functions of the host genome, including the possibility of activation of cellular oncogenes or production of a more general alteration in genomic functions through a mutagen-like mechanism. Human DNA contains sequences with homology to a specific restriction fragment of HSV-1.35 The fragment, termed ZtamHI-Z, is represented in 10 to 60 copies per human haploid genome and contains a 0.29 kb segment which is responsible for the homology. The possible significance of this homology in relation to HSV-induced transformation remains unclear but it could be related to host-viral interaction and host DNA rearrangement.
Further understanding of Pseudomonas aeruginosa’s ability to horizontally acquire virulence: possible intervention strategies
Published in Expert Review of Anti-infective Therapy, 2020
James Redfern, Mark C. Enright
Pseudomonas aeruginosa occupies a huge variety of environmental niches being a ubiquitous in many soils and watercourse habitats. These isolates are frequently indistinguishable from those colonizing and infecting humans. The species diversity and genome plasticity reflects this – the species has a very small core genome of a few hundred genes representing 1% of the species genes discovered thus far. Approximately half of the genes found in P. aeruginosa have only been seen in one isolate. A significant proportion of this pan-genome especially that related to antibiotic resistance is mobile, present on elements such as plasmids, transposons, and insertion sequences however the chromosome itself is also subject to high rates of recombinational change through HGT. The rapid detection and characterization of globally disseminated ‘High Risk’ genotypes (clones) that are particularly associated with enhanced virulence and MDR, XDR, and PDR resistance to antibiotics, through molecular diagnostics should enable more targeted treatments based on inferred antibiotic sensitivity from genome data or where no antibiotic is available, treatment with other agents in development such as therapeutic monoclonal antibodies or antimicrobial peptides. Anti-virulence molecules that interfere with inter-cell quorum sensing and signaling or approaches that destroy mixed strain and species biofilms where gene exchange occurs at high frequency represent future approaches for limiting the proliferation of P. aeruginosa genes for antibiotic resistance and virulence that represent an increasing threat to human health.
“I will survive”: A tale of bacteriophage-bacteria coevolution in the gut
Published in Gut Microbes, 2019
Luisa De Sordi, Marta Lourenço, Laurent Debarbieux
Here, we analyse a second source of genomic diversity, the emergence of bacterial resistance, one of the drivers of antagonistic evolution.5,8,29 Faecal pellets of mice in which P10 adaptation had occurred, yielded five MG1655 clones displaying different degrees of resistance to adapted P10 bacteriophages (Fig. 1A). The genomes of these five strains presented different mutations in the waaZ gene, which encodes a protein involved in the biosynthetic pathway for the core lipopolysaccharide (LPS) (Fig. 1B; Table S1). We identified four convergent paths of adaptation, characterised by gene disruption by insertion sequences (ISs), IS5 and IS2, at different gene positions. We hypothesise that independent convergent events leading to modifications of the LPS core biosynthesis pathway had served as the first step towards adaptation of the newly targeted strain MG1655, under the selective pressure of bacteriophage predation.
Genetic exchange and reassignment in Porphyromonas gingivalis
Published in Journal of Oral Microbiology, 2018
Ingar Olsen, Tsute Chen, Gena D Tribble
A high level of reticulation was seen in the phylogenetic networks constituted by 23 strains of P. gingivalis [8]. This indicated extensive horizontal gene transfer between the strains. There were variants in the major virulence factor of the Kgp proteinase, the Kgp C-terminal cleaved adhesion domain and the surface proteins FimA, FimCDE, Mfa l, RagAB, Tpr and PrtT. It was concluded that P. gingivalis uses domain rearrangements and genetic exchange to generate diversity in specific surface virulence factors. When the whole-genome sequences between ATCC 33277 and W83 were determined, extensive rearrangements were found between the two strains, possibly induced by different mobile elements (insertion sequences, miniature inverted-repeat transposable elements, and conjugative transposons) [10]. In ATCC 33277, many of the genes showed higher similarity to the genes of other bacterial species such as Bacteroides fragilis than to genes in W83. This suggested that they had been introduced to ATCC 33277 by horizontal gene transfer [10].