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Provided by the Springer Nature SharedIt content-sharing initiative. Advanced search. Skip to main content Thank you for visiting nature. Download PDF. Abstract This year is the th anniversary of the birth of Theodor Escherich, the German physician who discovered Escherichia coli. Main Since its discovery in the late nineteenth century, Escherichia coli has arguably become the best understood cellular life form, primarily because of its role as a model organism and the molecular biological 'workhorse' of numerous laboratories around the world.
References 1 Escherich, T. Google Scholar 2 Kaper, J. View author publications. Rights and permissions Reprints and Permissions. About this article Cite this article Hacker, J. Copy to clipboard. Search Search articles by subject, keyword or author. The healthy host usually has multilayered defenses that prevent the establishment of bacterial infection. Among the most effective of these defenses is the immune response. However, bacteria have evolved systems to avoid, subvert, or circumvent innate host defenses and to evade acquired specific immune responses of the host [ 34 ].
A capsule is a loose, relatively unstructured network of polymers that covers the surface of a bacterium. Further, increased serum resistance is often found among pathogenic bacteria, especially those associated with systemic infections [ 36 ]. Serum resistance is the ability to prevent complement activation on the bacterial cell surface and to inhibit insertion of the membrane attack complex into the bacterial membrane [ 34 ].
The feature is often based on the modifications in lipopolysaccharide LPS , which can be of two types: either attachment of sialic acid to LPS O antigen or changes in the LPS O antigen side chain [ 36 ]. However, other proteins can also be implicated in increased serum resistance; for example, the TraT protein of the surface exclusion complex involved in conjugation [ 37 ].
Another important protein of pathogenic E. Typical host immunity evading systems of pathogenic E. Toxins are the virulence factors that damage the host.
Exotoxins are toxic bacterial proteins that are excreted into the medium by growing bacteria or localized in the bacterial cytoplasm or periplasm and released during bacterial lysis. Exotoxins vary considerably in their activities and the target host cell types [ 36 ]. Typical toxins exotoxins of pathogenic E. However, E. The lipid portion lipid A is embedded in the outer membrane, with the core and O antigen portions extending outward from the bacterial surface.
Lipid A is the toxic portion of the molecule, and it exerts its effects only when bacteria are lysed. The toxicity of lipid A resides primarily in its ability to activate, complement, and stimulate the release of bioactive host proteins, such as cytokines [ 36 ].
Antibiotics are low-molecular-weight compounds that kill or inhibit growth of bacteria [ 36 ]. Antibiotic treatment is one of the main approaches of modern medicine to combat bacterial infections, including also E. However, bacteria evolved different mechanisms that confer resistances to antibiotics. Prevalence of invasive E.
The mechanisms of resistance to antibiotics are encoded in resistance genes. A list of typical E. Typical E. As many of the resistance genes are encoded on conjugative plasmids or conjugative transposons, they are easily transferred between different bacteria and hence spread in the population [ 36 ]. Bacteriocins are ribosomally synthesized, proteinaceous substances that inhibit the growth of closely related species through numerous mechanisms [ 51 ].
They are a heterogeneous group of particles with different morphological and biochemical entities. They range from a simple protein to a high molecular weight complex [ 52 ]. The bacteriocins with molecular masses below 10 kDa are designated as microcins [ 53 ]. Bacteriocins are potent toxins that are usually produced during stressful conditions and result in the rapid elimination of neighboring bacterial cells that are not immune or resistant to their effect.
Because of their narrow range of activity, it has been proposed that the primary role of bacteriocins is to mediate intraspecific, or population level, interactions [ 54 ]. The genetic determinants of most of the bacteriocins are located on the plasmids, apart from few, which are chromosomally encoded [ 52 ].
Bacteriocins of E. A relatively high frequency of colicin-encoding plasmids is found in isolates of pathogenic E. Especially microcins have been associated with pathogenic strains [ 54 ]. In a collection of E. Further, colicin insensitivity among these strains correlated with a higher prevalence of extraintestinal virulence factors [ 58 ]. Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.
Probiotic bacteria act via a variety of means, including modulation of immune function, production of organic acids and antimicrobial compounds, interaction with resident microbiota, interfacing with the host, improving the gut barrier integrity, and enzyme formation [ 61 ].
Several E. The probiotic E. Further it was shown that colonization of newborns led to reduced disease rates, lower incidence of allergies, and reduced mortality [ 62 ]. Probiotic E. In Table 9 contributions of E. Contributions of E. The following recombinant pharmaceuticals were set up to be in vivo synthesized in E. Further, E. To conclude, E. The differentiation between commensal and pathogenic strains is not easy, as among the healthy gut microbiota pathogenic strains are hidden, and also commensal strains can become pathogenic due to horizontal gene transfer of mobile genetic elements possessing virulence genes [ 71 ].
Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3. Help us write another book on this subject and reach those readers. Login to your personal dashboard for more detailed statistics on your publications. Edited by J. Marcelino Kongo. Almost all E. Stx2 has a number of variants e. The other pathotypes of diarrheagenic E. In general, diarrheagenic E. The E. Oct 19, Sep 28, Sep 04, Aug 25, Aug 08, View All Blog Articles.
The Most Recent E. Ch Preventing E. About E. Chapter 1 E. Escherichia coli — Diarrheagenic According to the group of virulence determinants acquired, specific combinations were formed determining the currently known E. Complex relationships among pathotypes Six E. Enterohemorrhagic E.
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