Clostridium Flashcards
Clostridium
gram positive, large rods, spore producing, strict anaerobes, fastidius, biochemically active, present in soil, alimentary tract and in feces, hemolysis (C. tetani, C. perfringens). Neurotoxic, Histotoxic, Enteropathogenic/enterotoxemic clostridia. C. tetani: many species affected (carnivores, poultry mostly resistant), spores introduced then germinate, vegetative form produces toxin, spastic paralysis, C. botulinum: many animals affected (carnivores mostly resistant), spores germinate in environment, vegetative form produces toxin, then it’s ingested, casuses flaccid paralysis. C. chauvoei, C. novyi, C. septicum (histotoxic). C. chauvoei: latent spores in body and after injury and reduced O2 tension in muscle leads to germination and vegetative replication; local necrosis, gas gangrene, “Blackleg”. C. novyi: latent spores as well but relocalization to liver and edema/shock/necrosis. C. septicum: abomasitis in sheep (Braxy) and gangrene. C. perfringens (enterotoxemic/enteropathogenic): commensal in GIT, toxin produced which has local and systemic effects; HGE, necrotic enteritis, enterotoxemia, gas gangrene, pulpy kidney in fat lambs (enteropathogenic). C. difficile: Abx associated diarrhea in man, necrotizing enterocolitis in horses. Dx: clinical signs, process of elimination. biochemical tests (GI contents (botulism), toxins (C. perfringens). Vaccines available for all.
Tetanus
From Clostridium tetanus. Tetanospasmin. Antigenically uniform, so vaccine can protect against a wide variety of species. Retrograde intra-axonal transport to CNS from motor-neuron terminals of muscle fiber. Prevents release of inhibitory neurotransmitter from alpha-motor neurone = spastic paralysis. Bound toxin is not neutralized by antitoxin.
Botulinum
Neurotoxins. Most potent toxins known. Pre-formed toxin, absorbed by GIT, circulates in blood. Acts at neuromuscular junctions of cholinergic nerves and peripheral autonomic synapses. Prevents Ach release, resulting in flaccid paralysis.
C. tetani
Neurotoxic Clostridium. Many species affected (carnivores mostly resistant, poultry nearly all resistant). Spores in environment, when introduced into host germinate, then vegetative replication and toxin produced (tetanospasmin). Spastic paralysis. Intra-axonal retrograde transport to CNS, then acts on motor neurons and prevents release of inhibitory neurotransmitter (works at pre-synaptic terminal). Dx by clinical signs. Vaccine available.
C. botulinum
Neurotoxic Clostridium. Many species affected (carnivores mostly resistant). Spores germinate in environment, found in rotting carcasses/decaying vegetation/contaminated canned food. After ingestion, systemic circulation, then flaccid paralysis. Prevents release of Ach at neuromuscular junctions/peripheral autonomic synapses (acts at pre-synaptic terminal). Death from paralysis of respiratory muscles. Dx by clinical signs/rule-outs. Vaccine available.
