Clostridial diseases Flashcards
What kind of bacteria are Clostridia?
Gram positive, anaerobic, spore-forming rods
What are examples of protein exotoxins?
Botulinum toxin, tetanus toxin, epsilon toxin
What are examples of exoenzymes?
Collagenase, proteinase, hyaluronidase, lecithinase
What are the most common routes of clostridial toxin entrance to the body?
Ingestion of preformed toxins, production in the GI tract, production in infected tissues/wounds
Which types of Clostridium cause neurologic disease?
Tetani, botulinum, perfringens type D
What types of Clostridium cause enterotoxemia?
Perfringens types A, B, C, and E
What types of Clostridium cause gas gangrene and malignant edema?
Chauvoei, septicum, sordelli, novyi type A and D
What types of Clostridium cause liver lesions?
Novyi type B, hemolyticum
Where is Clostridium tetani found?
In the soil and in the intestinal tract of herbivores
What are common routes of infection for Clostridium tetani?
Puncture wound of feet or soft tissues, uterus after calving, castration site (especially with elastrator bands), tail docking sites, infected umbilicus
What unique signs are associated with tetanus in ruminants?
Vaginal bruising, necrosis, retained placenta
What unique signs are associated with tetanus in yearling cattle?
Infection of tooth alveoli
Describe the pathophysiology of tetanus
Inoculated spores germinate in anaerobic conditions. In this process, they produce toxins and release them upon cell lysis. This can happen immediately after introduction of the spores or months later if an additional traumatic episode occurs.
What are the three toxins produced by tetanus?
Tetanolysin, tetanospasmin, non-spasmogenic toxin
Describe tetanolysin
Oxygen-sensitive hemolysin that destroys phagocytes and causes tissue necrosis; primarily allows for maintenance of infection
Describe tetanospasmin
A lipoprotein exotoxin that diffuses into the vascular system and binds with presynaptic motor end plates causing neurological effects by releasing glycine (so muscles cannot be relaxed)
Describe non-spasmogenic toxin
Produces over-stimulation of the sympathetic nervous system causing tachycardia, sweating, and hypertension
What clinical signs are associated with tetanus?
Stiffness, tremors, third eyelid prolapse (except in sheep), bloat, rigid paralysis, difficulty eating/chewing, respiratory arrest, death
How is tetanus treated?
With procaine penicillin G, local injection of antitoxin, debridement +/- acepromazine for sedation and relaxation
How can tetanus be prevented?
Vaccinate ewes prior to lambing and vaccinate lambs when they are tail docked/castrated and booster 2 to 4 weeks later
Why are ruminants more resistant to botulism than horses?
Botulism toxins are partially destroyed in their rumen
Where are the botulism types usually found?
B- decaying vegetable matter
C and D- intestinal tract of carcasses of rodents, birds, and cats
Describe the pathophysiology of botulism
Toxins act at presynaptic cholinergic neuromuscular junction and postganglionic parasympathetic nerve endings to block the release of acetylcholine. Toxin binding is irreversible so function only returns after regeneration occurs.
What are the four sources of botulism toxin?
Forage poisoning, carrion associated, wound associated, toxicoinfectious
Describe forage poisoning
Seen in adults following ingestion of preformed toxin in spoiled feed materials (grains, silage, hay), usually type B