Toxins
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Classification
- C.welchii is one of the most prolific of toxin producing bacteria forming at least 12 different toxins , besides many other enzymes and biological active substances.
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C. perfringens
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Type
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Alpha
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Beta
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Epsilon
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Iota
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A
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+
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-
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-
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-
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B
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+
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+
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+
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-
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C
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+
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+
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-
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-
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D
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+
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-
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+
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-
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E
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+
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-
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-
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+
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Alpha toxin is produced by all types. Mostly by type A strains. It is lethal, dermonecrotic and haemolytic.
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This is a lecithinase C (phospholipase) that attacks cell membranes causing cell death and destruction and also responsible for Nagler’s reaction .
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It is haemolytic for the red cells of most species except horse and goat. This toxin gives a zone of partial haemolysis on blood agar.
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The haemolysis is of hot-cold variety being best seen after incubation at 370C followed by chilling at 40C.
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Beta toxin is lethal and necrotising. It is sensitive to trypsin and this explains the predilection of types B and C for neonates as colostrum has anti trypsin activity.
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It is a labile toxin and may be destroyed if there is a delay in small intestinal contents, containing the toxin, reaching the laboratory.
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Epsilon toxin is secreted as a protoxin (proto toxin) and is activated in the intestines by proteases such as trypsin.
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Pulpy kidney disease is not usually seen in neonatal lambs as colostrum contains an antitrypsin factor that can prevent the epsilon toxin being activated.
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The toxin itself increases gut permeability, assuring absorption of the toxin into the blood stream.
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It damages vascular endothelium (including blood vessels in the brain) leading to fluid loss and edema.
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This epsilon toxin can be regarded as an enterotoxin and neurotoxin.
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Iota toxin is also produced as a protoxin and is not unique to C.perfringens type E as it is also formed by C.spiroforme and C.difficile
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Besides several minor toxins are produced such as the theta (haemolysin), Kappa (collagenase), lambda (Proteinase), Mu(hyaluronidase) and Nu(DNase) – all these may contribute to tissue damage.
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Based on the type of toxin productions, Clostridium perfringens are classified into 5 types
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C.perfringens types
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Host
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Disease
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A
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Enterotoxins
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Human
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Food poisoning
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Alpha
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Lambs
Broiler chickens
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Enterotoxaemic jaundice
Necrotic enteritis
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B
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Beta and alpha
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Lambs under 3 weeks old
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Lamb dysentry
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C
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Beta and alpha
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Piglets 1-3days old
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Haemorrhagic enteritis
(Clostridial enteritis)
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Broiler chickens
(2 weeks old)
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Necrotic enteritis
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Adult sheep and goats
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Struck
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D
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Epsilon
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Sheep all ages (except neonates)
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Pulpy kidney disease (over eating disease)
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E
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Iota and alpha
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Calves and lambs
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Enterotoxaemia (Haemorrhagic enteritis)
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Last modified: Monday, 4 June 2012, 4:30 AM
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