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Metal economy in host-microbe interactions

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194971 Year: Pages: 215 DOI: 10.3389/978-2-88919-497-1 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Science (General)
Added to DOAB on : 2015-11-16 15:44:59
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From simple inorganic catalysts to vital biological cofactors, divalent transition metals are instrumental to electron transfers, catalysis and signaling. Their natural ability to bind, exchange and react with organic molecules including oxygen requires from living cells to regulate uptake with metabolic activities, sensing and chaperoning, distributing and storing, or excreting excess to prevent detrimental biochemical reactions. Since transition metal deficiency and overload both limit cell growth it is no surprise that the immune system evolved a dual strategy, of metal starvation or intoxication, to thwart microbial invasions. Like environmental metal availability determined biological use it also shaped host-microbe metal economy: Fe and Mn, available early in evolution and still required rather ubiquitously, are generally withheld by host in response to infection; Zn and Cu, which became bioavailable later, essentially to eukaryotic cells may be bombarded toward invaders. Successful microbial pathogens have evolved elaborate counter-measures to cope with host metal defenses. This research topic aims to review and discuss metal currencies in host-microbe interactions focusing on new findings about micro-organism pathogenesis determinants in the face of host innate strategies to interfere with microbial physiology.

Keywords

metal --- Virulence --- host --- pathogen --- transporter --- exporter --- regulation

Shiga toxin-producing Escherichia coli in human, cattle and foods. Strategies for detection and control

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192939 Year: Pages: 107 DOI: 10.3389/978-2-88919-293-9 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Science (General)
Added to DOAB on : 2015-12-10 11:59:07
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Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen associated with both outbreaks and sporadic cases of human disease, ranging from uncomplicated diarrhoea to haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS). STEC affects children, elderly and immuno-compromised patients. STEC is capable of producing Shiga toxin type 1 (Stx1), type 2 (Stx2) or both, encoded by stx1 and stx2 genes, respectively. These strains are likely to produce putative accessory virulence factors such as intimin (encoded by eae), an enterohaemolysin (EhxA) and an autoagglutinating protein commonly associated with eae-negative strains (Saa), both encoded by an enterohaemorrhagic plasmid. Several studies have confirmed that cattle are the principal reservoir of STEC (O157 and non-O157:H7 serotypes) and many of these serotypes have been involved in HUS and HC outbreaks in other countries. Transmission of STEC to humans occurs through the consumption of undercooked meat, vegetables and water contaminated by faeces of carriers and by person-to-person contact. Diagnostic methods have evolved to avoid selective diagnostics, currently using molecular techniques for typing and subtyping of strains. Control is still a challenge, although there are animal vaccines directed against the serotype O157:H7.

Keywords

STEC --- Cattle --- Food --- environment --- Virulence Factors

New anti-infective strategies for treatment of tularemia

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889193394 Year: Pages: 78 DOI: 10.3389/978-2-88919-339-4 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Science (General)
Added to DOAB on : 2016-03-10 08:14:32
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Francisella tularensis, the causative agent of tularemia, is a paradigm among human pathogens. This Gram-negative bacterium has an intracellular lifestyle, which probably reflects an adaptation to its natural animal and protozoa reservoirs. This is one of the most infectious agents in humans and animals; only a few bacteria are needed to induce a severe infection in both types of hosts. The clinical presentation and severity of human tularemia varies according to the portal of entry of bacteria, the bacterial inoculum, the virulence of the infecting strain, and the immune response of the host. Although most infections occur after direct inoculation of bacteria through the skin (through skin wounds or bites of arthropods), pneumonia due to inhalation of infected aerosols is the most feared of the clinical forms of the disease, particularly in the context of biological threat. Two subspecies are responsible for tularemia (subsp. tularensis and subsp. holarctica), and several clades have been described for each, which might be associated with changes in disease severity in humans. Tularemia is also more severe in people with an impaired immune response. No safe vaccine is currently available for prophylaxis of tularemia in humans. On the other hand, control of proliferation of F. tularensis in wildlife is not feasible. Thus, only the anti-infective agents are used for treatment and prophylaxis of human tularemia. The standard options include aminoglycosides (gentamicin), tetracyclines (eg, doxycycline) and fluoroquinolones (eg, ciprofloxacin). The selection of acquired resistance to these antibiotics in F. tularensis, especially in the context of a biological threat, may quickly limit the therapeutic options. New prophylactic and therapeutic alternatives must be developed rapidly. The present Research Topic focuses on potential new strategies for treatment of tularemia, including the development and evaluation of new compounds having proper antibacterial activity, reducing the virulence of F. tularensis or enhancing the immune host response.

Pathogenesis of Leptospira

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456499 Year: Pages: 103 DOI: 10.3389/978-2-88945-649-9 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Internal medicine
Added to DOAB on : 2019-01-23 14:53:43
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The present eBook, consisting of a compilation of research and review articles, focuses on the features and mechanisms adopted and explored by pathogenic leptospires to successfully establish infection in the host. Additionally, this eBook provides information to support future work focused on the development of new prevention approaches against this important yet neglected zoonotic disease.

Novel Molecular Approaches to Target Microbial Virulence

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ISBN: 9783110449501 9783110449617 Year: Pages: 87 DOI: 10.1515/9783110449501 Language: English
Publisher: De Gruyter
Subject: Biotechnology --- Microbiology --- Internal medicine
Added to DOAB on : 2016-01-06 13:06:10
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Microbial infections still represent one of the major causes of mortality and morbidity worldwide. Irrational usage of antimicrobials has lead to increased resistance, causing clinical, social and economical disabilities. Therefore, one of the major challenges of scientists is to develop novel alternative methods to handle infections and reduce resistance and other side effects produced by the actual therapies. The aim of this book is to offer a perspective on novel approaches to handle infections by using naturally-derived products in order to modulate the virulence of pathogens, without the risk of developing resistance. We intend to highlight the utility of microbial, vegetal and animal–derived compounds with potential antimicrobial activity by exploiting their effect on microbial virulence. Furthermore, this book aims to reveal the potential to assimilate recent bio-technological findings, like the usage of nanotechnology as efficient shuttles for stabilizing, improved targeting and the controlled release of natural products in order to efficiently fight infections.

Ecology, Virulence and Detection of Pathogenic and Pandemic Vibrio Parahaemolyticus

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889199129 Year: Pages: 132 DOI: 10.3389/978-2-88919-912-9 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Microbiology
Added to DOAB on : 2016-01-19 14:05:46
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Vibrio parahaemolyticus is a gram negative, halophilic bacterium that occurs in the coastal and estuarine environments worldwide and is implicated in several cases of seafood-born gastroenteritis around the globe. However, not all strains of V. parahaemolyticus are pathogenic. Clinical isolates of V. parahaemolyticus most often produce either the thermostable direct haemolysin (TDH) or TDH-related haemolysin (TRH) encoded by tdh and trh genes, respectively. A pandemic clone of O3:K6 which was first detected in Kolkata (India), has been responsible for many outbreaks in Asia and the USA. With the emergence of pandemic clone of V. parahaemolyticus, this organism has assumed significance. Although most of the V. parahaemolyticus outbreaks are invariably related to seafood consumption, pathogenic strains are rarely isolated from seafood. Virulent strains producing TDH or TRH and the pandemic clone, which is responsible for most of the outbreaks (that have occurred after 1996) have been rarely isolated from seafood and other environmental samples. This could be due to the occurrence of pathogenic strains in the estuarine environment at a lower level compared to non-pathogenic strains. Another reason can be that the pathogenic stains are more sensitive to dystropic conditions in the aquatic environment and rapidly become non-culturable. Similarity in growth kinetics between virulent and non-virulent strains also made the isolation of virulent strains from the aquatic environment difficult. Several studies were done to determine the factors responsible for an increased virulence and persistance of pandemic clone. However, none of those studies were conclusive. Several researchers have proposed various genetic markers for specific detection of pandemic clone of V. parahaemolyticus. But many of those genetic markers were found to be unreliable. Recently, seven genomic islands (VPaI-1 to VPaI-7) unique to pandemic clone were identified. This Research Topic is dedicated to improve our current understanding of ecology, pathogenesis and detection of pathogenic and pandemic clone of V. parahaemolyticus, and will also strive to identify areas of future development.

Antimicrobial Resistance and Virulence Common Mechanisms

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451814 Year: Pages: 138 DOI: 10.3389/978-2-88945-181-4 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2017-08-28 14:01:09
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Multiple relationships exist between antimicrobial resistance and bacterial virulence, and the spread of clones combining multiple antibiotic resistance and a high virulence level is an increasing problem. It was previously described how mutation-driven or horizontally acquired resistance mechanisms can also have effects on virulence. It was also reported that mobile genetic elements often carry both resistance determinants and virulence-modulating genes, which favors the co-selection of both traits. In the present volume, we present a collection of articles which document additional aspects of the interactions between antimicrobial resistance and virulence in bacteria, and describe their potential therapeutic consequences.

The Role of Iron in Bacterial Pathogenesis

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456628 Year: Pages: 156 DOI: 10.3389/978-2-88945-662-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Internal medicine
Added to DOAB on : 2019-01-23 14:53:43
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The collection of articles published in this eBook represent different facets of the interactions between pathogens and their host concerning the battle for iron. Pathogens have developed different strategies to acquire iron from their host. These include the production of siderophores, heme acquisition and ferrous iron uptake.

The pathogenic Yersiniae - advances in the understanding of physiology and virulence

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192588 Year: Pages: 199 DOI: 10.3389/978-2-88919-258-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Internal medicine
Added to DOAB on : 2015-11-16 15:44:59
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For decades, pathogenic Yersinia have served as an inventive model organism for researchers seeking to understand the complexities of bacteria-host cell interactions. In fact, seminal studies on Yersinia virulence mechanisms contributed to the emergence and recognition of the research field - cellular microbiology. Researching Yersinia infection biology continues to identify and define fascinating virulence and survival mechanisms that advance and expand existing perceptions of bacterial-host encounters. This also includes research that defines how the pathogenic Yersiniae respond to diverse physicochemical stimuli to spatially and temporally control this armory of customized virulence and survival factors. Yet additional research demonstrates how the application of powerful whole genomic-based methodologies can open new frontiers that further facilitate understanding of bacterial evolution and pathogenicity. This Research Topic is therefore focused on presenting and summarizing new developments in Yersinia patho-physiology through highlighting cutting- edge studies on the Yersinia-host cell interaction and the network of regulatory control mechanisms that define this outcome.

Agrobacterium biology and its application to transgenic plant production

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195749 Year: Pages: 165 DOI: 10.3389/978-2-88919-574-9 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General) --- Botany
Added to DOAB on : 2016-02-05 17:24:33
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The broad host range pathogenic bacterium Agrobacterium tumefaciens has been widely studied as a model system to understand horizontal gene flow, secretion of effector proteins into host cells, and plant-pathogen interactions. Agrobacterium-mediated plant transformation also is the major method for generating transgenic plants for research and biotechnology purposes. Agrobacterium species have the natural ability to conduct interkingdom genetic transfer from bacteria to eukaryotes, including most plant species, yeast, fungi, and even animal cells. In nature, A. tumefaciens causes crown gall disease resulting from expression in plants of auxin and cytokinin biosynthesis genes encoded by the transferred (T-) DNA. Gene transfer from A. tumefaciens to host cells requires virulence (vir) genes that reside on the resident tumor-inducing (Ti) plasmid. In addition to T-DNA, several Virulence (Vir) effector proteins are also translocated to host cells through a bacterial type IV secretion system. These proteins aid in T-DNA trafficking through the host cell cytoplasm, nuclear targeting, and T-DNA integration. Genes within native T-DNAs can be replaced by any gene of interest, making Agrobacterium species important tools for plant research and genetic engineering. In this research topic, we provided updated information on several important areas of Agrobacterium biology and its use for biotechnology purposes.

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