Clostridium Flashcards
What are the main 3 morphological characteristics of Clostridium?
- straight or slightly curved rods
- Gram positive
- produce endospores, where the size, shape, and location can be used for ID
What’s unique about Clostridium cultures? What is their most common mode of energy production?
typically emit putrid odors
peptide catabolism
What kind of respiration does Clostridium undergo?
anaerobes
How does Clostridium respond to catalase and oxidase tests?
negative
negative
Clostridium are motile bacteria. What species is the exception?
C. perfringens
What is necessary for Clostridium growth on agar? How does C. perfringens grow in blood agar?
enrichment of the media
surrounded by zones of double hemolysis
What are the main 3 locations that Clostridium is found?
- soil (saprophytes)
- alimentary tracts of animals (intestinal flora)
- feces
How are Clostridium grouped? What are the 3 groups?
according to the mode and sites of action of their exotoxins
- neurotoxic
- histotoxic
- enteropathogenic and enterotoxemia-producing
Where are sequestered endospores of Clostridium typically found? What happens when they’re activated?
muscle or liver
produce disease
How do Clostridium perfringens, C. tetani, and chauvoei compare morphologically?
C. perfringens: large, wide rods that rarely form endospores
C. tetani: thin rods that produce terminal endospores (drumstick)
- C. chauvoei: medium-sized rods that produce lemon-shaped endospores
What are the 2 neurotoxic Clostridia? Where do the genes for their neurotoxins come from?
- C. tetani - plasmids
- C. botulinum - chromosomes, plasmids, bacteriophages
What are the 10 serotypes of C. tetani based on?
flagellar antigens and geographic strain origin
What makes the C. tetani vaccine efficient?
tetanus neurotoxin (TeNT) is antigenically uniform (not altered by mutations)
What are the main 2 reservoirs of C. tetani?
- widely distributed in the soil
- transient in the intestine
What is the occurrence of tetanus commonly linked to? How can this happen?
introduction of spores into traumatized tissue
- contaminated syringes
- penetrating nail wounds on foot
- barnyard surgery
- use of rubber bands for castrating and docking
- ear tagging infections
- shearing wounds
- post-partum uteroine infections
- perinatal umbilical infections
- small fights
What is the neuroparalytic intoxication of tetanus characterized by? What causes this?
tonic-clonic convulsions
protein neurotoxin (tetanospasmin)
(tetanus = taut)
All mammals are susceptible to tetanus to varying degrees. How do animals compare? How susceptible is poultry? What is true in all animals infected?
horses, humans, ruminants, and swine are more susceptible than carnivores
poultry are highly resistant
mortality rate is high
How does tetanospasmin cause spastic paralysis?
zinc endopeptidase binds ti the neurons, which releases GABA and glycine, the major inhibitory neurotransmitters that stop muscle contraction
however, tetanoplasmin hydrolyzes the docking protein (VAMP, synaptobrevin) required by inhibitory transmitter-containing vesicles to fuse with the presynaptic membrane, causing the synapse to degenerate which takes weeks to months to regenerate
What are the 5 steps to C. tetani pathogenesis?
- anaerobic environment allows spores to germinate
- toxin diffuses via vascular channels or peripheral nerve trunks
- toxin attaches to receptors on nearest cholinergic nerve and is internalized within a vesicle
- vesicle travels retrograde inside the axons to the cell bodies in the ventral horns of the spinal cord
- toxin causes innervated muscles to remain in sustained clonic or tonic spasms and can travel within the cord to other levels affecting additional muscle groups
(SPASTIC PARALYSIS)
How can the spores of C. tetani be visualized microscopically?
Malachite green stain
(Gram positive!)
What is the incubation period of C. tetani? What are the major early signs? When is mortality the highest?
few days to several weeks
stiffness, muscular tremor, increased responsiveness to stimuli
mortality is at least 50% and highest in young animals
What are 5 common signs of tetanus is horses, ruminants, and swine?
- retraction of third eyelid
- erectness of ears
- teeth grinding
- tail stiffness
- lockjaw —> feeding impossible
What is the most common sign of tetanus in ruminants? What is sawhorse?
bloat
rigidity of extremities that leads to recumbence