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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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Abstract

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.

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.

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