Chemical and spectroscopic studies of the capsular polysaccharides of some klebsiella and escherichia coli serotypes
- Authors: Stanley, Shawn Mark Ross
- Date: 1990
- Subjects: Polysaccharides , Klebsiella , Escherichia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3736 , http://hdl.handle.net/10962/d1001525
- Description: The work described in this thesis forms part of an international programme concerned with the structure elucidation of the capsular antigens of some Enterobacteriaceae. Many of the Klebsiella and some of the Escherichia coli are pathogenic to man and, hence, they are of interest. The virulence of bacteria is a multifactorial phenomenon, in which characteristic traits of bacteria and their hosts play comparable and complementary roles. It is accepted that pathogens are more virulent when encapsulated, because, nearly all disease causing bacteria have a capsule when freshly isolated from the host. This increase in pathogenicity is related, in part, to the capsular polysaccharides' ability to avoid or attenuate the host defence mechanisms. In the majority of cases the protective aspects of the capsule are overcome in the latter stages of infection when the formation of specific antibodies by the host has occurred. However there are situations in which an immune state of the infected host is virtually never reached, and susceptiblity to the infecting bacteria is maintained even in the advanced stage of an infection. Explanation of this phenomenon becomes possible by analysing the structure of the polysaccharides. The inability of the host to raise an immune response to the capsule may be because the structure of the polysaccharide is similar or identical to the host's carbohydrates. The serological and pathogenic relatedness of encapsulated E. coli and Klebsiella, to the encapsulated strains of other genera, is based on structural identity or similarity of the respective capsules. Capsular polysaccharides are analysed by both chemical and instrumental methods, and, at present, nuclear magnetic resonance spectroscopy is the most important analytical technique
- Full Text:
- Date Issued: 1990
A structural study of the capsular antigens of escherichia coli K36 and klebiella K68
- Authors: Stanley, Shawn Mark Ross
- Date: 1987 , 2013-03-11
- Subjects: Enterobacteriaceae , Klebsiella , Escherichia , Antigens
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3814 , http://hdl.handle.net/10962/d1004613 , Enterobacteriaceae , Klebsiella , Escherichia , Antigens
- Description: From Introduction: Bacterial cells all have a cytoplasmic membrane (see Figure 1) which regulates the movement of ions and molecules into and out of the bacterium. Enclosing this membrane is a cell wall of which there are two general types, which are differentiated by the Gram stain(02) as being either gram positive or gram negative (depending upon whether they hold the gram stain after washing with ethanol). The cell wall provides the cell with shape and rigidity and is composed, in the case of gram positive types, of peptidoglycan, and in the case of gram negative bacteria, of a peptidoglycan and an outer membrane (see Figure 2). The peptidoglycan layer, common to both cell wall types, consists of a backbone of alternating units of N-acetylglucosamine and N-acetylmuramic acid to which peptides are attached by amide links. This heteropolymer is a highly cross linked mosaic and this gives it strength and rigidity. In gram positive bacteria, this layer also contains two carbohydr ate antigens, a simple polysaccharide and a teichoic acid; these are usually the type specific or major group antigens of the bacterium. Many of the bacteria also produce exopolysaccharides (see Figure 3) either as discrete capsules (for example, the Enterobacteriaceae K antigens) or unattached slime layers (for example, the Enterobacteriaceae M antigens). The vast majority of these polysaccharides are heteroglycans(03) composed of contiguous oligosaccharide repeating units. Their monosaccharide components are largely neutral hexoses, 6-deoxy hexoses and also amino sugars. (03) Pentose units are rare. (03) The capsular polysaccharides usually have a high content of acidic constituents such as uronic acids, phosphate groups, or pyruvate ketals. (01) , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
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- Date Issued: 1987