bovine pathogens Flashcards
(49 cards)
What is the hallmark of histotoxic Clostridia spp?
Enthusiastic toxigenesis (meaning that the toxins generally explain the disease seen)
What are three characteristics of Clostridia spp?
- Gram-positive
- Spore-forming
- Strict anaerobes
What does histotoxic mean?
Histotoxic means it is damaging to the tissue. Just like how C. botulinum is neurotoxic and C. piliforme is enterotoxic, some species are histotoxic.
There is overlap too. For example, C. perfringens is both histotoxic and enterotoxic.
Name four histotoxic Clostridia spp.
- C. perfringens
- C. septicum
- C. chauvoei
- C. novyi
Which general disease patterns does C. septicum cause?
- Malignant edema associated with traumatic wounds
- Myonecrosis due to toxicogenesis
- Enteric infection and braxy (sudden death) in lambs and calves
How does death occur from C. septicum?
As the infection spreads along muscles, hemorrhage, edema, and necrosis develop rapidly causing death in less than 24 hours.
What are four necropsy findings of C. septicum?
- Gangrene of infected skin
- Foul putrid odour
- Gelatinous exudate in the subcutaneous and intramuscular connective tissue
- Dark red hemorrhagic muscle
In cattle, C. septicum is too similar to C. chauvoei (blackleg), therefore differentiation made on necropsy is unreliable.
True. Laboratory confirmation is the only certain procedure
Horses and pigs are susceptible to malignant edema but not to _____________
Blackleg, therefore this might be able to help with your diagnosis (therefore horses and pigs are less likely to have C. chauvoei versus C. septicum)
What is the best laboratory test to use to diagnose C. septicum?
Fluorescent-antibody staining of C. septicum from a tissue smear
The presence of C. septicum in a specimen is always indicative of its infection.
False. C. septicum is an extremely active postmortem invader from the intestine, therefore its presence in a specimen taken from an animal that has been dead for ≥24 hr is not significant.
Which types of C. novyi are virulent in domestic animals?
Type A, type B and type D
What is ‘black disease’? Which bacteria causes ‘black disease’?
Black disease is the common name for infectious necrotic hepatitis. This is caused by C. novyi type B
Which bacteria causes ‘big-head disease’?
C. novyi type A. A ‘big-head’ lesion is classic of this disease as it causes severe edema.
What is ‘red disease’? Which bacteria causes ‘red disease’?
Red disease is the common name for bacillary hemoglobinuria of cattle. This is caused by C. novyi type D
C. haemolyticus is another name for which bacteria?
C. novyi type D
What is ‘blackleg’? Which type of bacteria causes ‘blackleg’?
Blackleg is the common term for necrotizing emphysematous myositis. Blackleg is caused by C. chauvoei
What are the classic lesions seen with blackleg?
Infiltration of the musculature with gas bubbles that have a characteristic rancid smell. The hindquarters usually have the most severe changes.
What is the pathogenesis of blackleg?
- Spores enter the bloodstream and travel to organs and tissues (particularly muscles)
- Spores remain dormant until trigger (usually an injury)
- Trigger reduces blood flow and supply of oxygen to the tissues (causing bacteria to multiply and produce a local infection and toxins)
Which four toxins do C. chauvoei release?
- α (leukocidin)
- γ (hyaluronidase)
- δ (hemolysin)
- Neuraminidase
What are four necropsy findings of C. chauvoei?
- Laying with affected hind leg stuck out.
- Bloating of carcass and blood stained frothy exudates from the nostrils and anus
- Dark red to black muscle of the loin, back or leg
- Sponge-like bubbly appearance of the muscles with a peculiar rancid odour
Remember, this looks very similar to a C. septicum infection!
What is the best tissue to sample to test for blackleg?
The affected muscle (primarily skeletal muscle, although cardiac muscle or liver can be used)
Which diagnostics tests should you use to test for blackleg?
- Fluorescent antibody test
- Immunohistochemistry
True or False: There is a vaccine that prevents all clostridia infections in cattle.
False. There is a vaccine that prevents many infections, but not every type of clostridia. The 7-way vaccine that protects against:
- Clostridium chauveoi (blackleg)
- Clostridium septicum (malignant edema)
- Clostridium novyi (black disease)
- Clostridium perfringens (enterotoxemia)
