Veterinary bacteriology: information about important bacteria
|Species/Subspecies:||Corynebacterium diphtheriae subsp. diphtheriae|
|Category:||Primarily of interest in human medicin|
|Etymology:||Genus name: club-shaped bakterium (bacterium means small rod).|
Species epithet: of diphtheria
Subspecies epithet: see Species epithet.
|Significance:||Diphtheria is nowadays a rare disease in Sweden and other developed countries.
|Type Strain:||ATCC 27010 = NCTC 11397.|
|Macromorphology (smell):||Small, gray and translucent colonies (1-3 mm in diameter). Some strains give hemolysis on blood agar.|
|Micromorphology:||Nonmotile pleomorphic rod (1-8 x 0,3-0,8 µm). Form ramified aggregates, which look like chineese letters).|
|Gram +/Gram -:||G+|
|Other Enzymes:||Esculinase -, urease -|
|Fermentation of carbohydrates:||
Fructose ?, mannose ?, xylose -.
|Disease:||Diphtheria in humans. (Mastitis and dermatitis in cattle, which is rare.)
|Hosts:||Humans (primarely children) and cattle (rare)|
|Virulence Factors:||The structural gene for the diphtheria toxins (the tox genes) are carried by a family of closely related corynebacteriophages. The Beta-phage (B-phage) is the most extensively studied phage. A lytic cycle of the phage is not required for production of the diphtheria toxin. The diphteria toxin is a so-called AB toxin, which cleave NAD into nicotinamide and ADP-ribose (ADPR). ADPR is then irreversibly transferred to elongation factor 2 of the host cells and this results in inhibition of protein synthesis. The diphtheria toxin is, therefore, also called ADP-ribosylating toxin.
Lethal dose of the difteria toxin for humans is about 0.1 μg per kg of bodyweight, which is 50-100 times more than the lethal dose for the botulinum neurotoxin.
|16S rRNA Seq.:|
||176 species and 13 subspecies are described within the genus Corynebacterium. However, not all names have been approved yet and some species have been affiliated to another genus. The genus Corynebacterium is closely related to the genera Mycobacterium, Nocardia, Rhodococcus and Crossiella.|