Clostridium haemolyticum
| Clostridium novyi | |
|---|---|
| Scientific classification | |
| Kingdom: | Bacteria |
| Phylum: | Firmicutes |
| Class: | Clostridia |
| Order: | Clostridiales |
| Family: | Clostridiaceae |
| Genus: | Clostridium |
| Species: | C. novyi |
| Binomial name | |
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Clostridium novyi |
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Clostridium novyi (oedematiens) a Gram-positive, endospore- forming, obligate anaerobic bacteria of the class clostridia. It is ubiquitous, being found in the soil and faeces. It is pathogenic, causing a wide variety of diseases in man and animals. It comes in three types, labelled A, B, and a non-pathogenic type C distinguished by the range of toxins they produce. Some authors include Clostridium haemolyticum as Clostridium novyi type D. C novyi is closely related to Clostridium botulinum types C and D as Yoshimasa Sasaki et al. have demonstrated by 16S rDNA sequence analysis.
Growth in culture proceeds through 3 stages: Initial growth wherein no toxin is produced; vigorous growth wherein toxin is produced; and spore formation wherein endospores are formed and toxin production decreases. It is suggested that type C may be type B that forms spores more readily so does not go through the toxin-production stage.
Isolating and identifying C novyi is difficult due to its extreme anaerobic nature. Commercial kits may not be adequate.
It is also fastidious and difficult to culture, requiring the presence of thiols.
The alpha-toxin of Clostridium botulinum types C and D, is similar to the C novyi beta-toxin. The A and B toxins of Clostridium difficile show homology with the alpha-toxin of C novyi as does the lethal toxin of clostridium sordellii.
The alpha-toxin is characterised as lethal and necrotizing.
The type A alpha-toxin is oedematising. It acts by causing morphological changes to all cell types especially endothelial cells by inhibition of signal transduction pathways, resulting in the breakdown of cytoskeletal structures. The cells of the microvascular system become spherical and the attachments to neighbouring cells are reduced to thin strings. This results in leakage from the capillaries, leading to oedema. The threshold concentration for this action to occur is 5 ng/ml (5 parts per billion) with 50% of cells rounded at 50 ng/ml.
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