BIO 2110-Section 303
December 04, 2011
Clostridium Difficile is known to be a notorious infection to cause foul smelling diarrhea, very well known to almost every healthcare worker. It is one of the most difficult infections to treat in the current healthcare industry, and most often related to the use of antibiotics during healthcare treatment. Clostridium Difficile is a spore-forming, gram-positive anaerobic toxin-producing bacterium that is a “common” inhabitant of the colon flora in human infants and sometimes in adults. Clostridium Difficile contain peptidoglycan in their cell walls. As spores, rod-shaped, the bacteria look like drumsticks, with a bulge located at one end. C. Difficile produces an S layer (polysaccharide capsule) that makes it pathogenic. Five of 15 strains of Clostridium Difficile are known to possess multiple polar fimbriae, which were 4–9 nm in diameter and up to 6 μm long. There was no direct correlation between the presence or absence of fimbriae and the toxigenic status of the organism. C. Difficile moves via peritrichous flagella. These flagella are evenly spread around the surface of each cell and which allows the bacillus to be highly motile. The bacillus are able to move by a tumbling motion and by movement in a forward direction. Nine toxigenic and six non-toxigenic strains of Clostridium Difficile, of varying virulence in a study of antibiotic-associated colitis, were examined for the presence of a capsule. All strains possessed a capsule, which was either loose-knit or compact, sometimes with attached globular masses. The possession of a capsule following in vitro growth does not appear to correlate with the virulence status of these strains of C. Difficile. The pathogenicity of C. Difficile due to spore-forming capacity. The spore form of the organism is resistant to gastric acid and can therefore readily pass through the stomach to the intestine, where it changes to a vegetative life cycle. Biofilms are 3-dimensional structured communities of microorganisms that form on and attach to surfaces. C. Difficile forms biofilms in clinical cases of pseudomembranous colitis. Microbial biofilms are defined as a ‘surface-associated microbial community commonly enveloped within an extracellular matrix’. The primary characteristic of biofilms are a phenotype markedly different from that of identical microorganisms growing planktonically. C. Difficile is an obligate fermenter, and exhibits optimal growth in blood agar at human body temperatures in the absence of oxygen. The metabolism of C. Difficile is in large part adapted to life in the intestinal tract. It produces enzymes that degrade nutrients abundant in the intestine. Carbohydrates are the preferred nutrient source, and C. Difficile is able to metabolize a wide range of carbohydrates. The bacteria also have a relatively unique ability to utilize ethanolamine, an abundant phospholipids provided by the host’s dietary intake, as a carbon and nitrogen source. C. Difficile has the enzyme that catalyzes the decarboxylation of p-hydroxyphenylacetate (a tyrosine degradation product) to p-crysol, a compound that stunts bacterial growth. C. Difficile produces and tolerates high concentrations of p-crysol, giving it a competitive advantage over the normal bacterial flora in the intestine. C. Difficile is found throughout nature, especially in soil. It exhibits optimal growth in blood agar at human body temperatures in the absence of oxygen. It can remain dormant in hospitals in the form of spores until patient inoculation. After giving antibiotics, C. Difficile overgrows in the intestinal tract. Mucosa of the gut allows C. Difficile adherence to the colonic epithelium. C. Difficile are anaerobic, and live in the absence of oxygen. In the presence of oxygen, the vegetative form of C. Difficile can survive up to 24 hours on an inanimate surface; whereas, C. Difficile spores can survive up to 2 years on...
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