Unit 3: Clostridium Flashcards
In regards to oxygen, what type of organisms are in the genus Clostridium?
obligate anaerobes
What do bacteria in the genus Clostridium look like on gram stain?
gram-positive, large, rods
What do the spores of Clostridium look like?
usually oval, often greater than the diameter of the rod
What is the best way to identify different Clostridium species?
MALDI-TOF-MS
What do many veterinary professionals rely on for Clostridium diagnosis?
clinical signs
What is the natural habitat of the genus Clostridium?
intestine, damaged tissue, decaying organic material
What are the two broad types of clostridia?
those that do not actively invade and multiply (rely on toxin production) and those that invade and multiply in the tissues
True or False: Clostridia produce diseases that are generally contagious from one animal to another.
False
How are Clostridia spores killed?
By boiling them for 15 minutes or autoclaving for 15-20 minutes
What is most of the disease associated with Clostridia caused by?
exotoxins
What does Clostridium tetani cause?
tetanus (lockjaw)
What does Clostridium tetani look like on gram stain?
gram positive, single, slender rod with terminal spores
What do colonies of Clostridium tetani look like?
they are beta hemolytic, swarming, and may have a very foul odor in broth
What is the natural habitat of Clostridium tetani?
soil as spores, fecal material, readily found in horse and human feces
What toxins does Clostridium tetani release?
Tetanospasmin, hemolysin, and non-spasmogenic toxin
What is tetanospasmin responsible for?
clinical disease due to Clostridium tetani
What does tetanospasmin do?
it blocks neurotransmitter release, specifically glycine and gamma-aminobutyric acid at the level of the spinal cord and brainstem. The inhibitory nerve network is affected and results in continuous spasms of opposing groups of muscles. The toxin binds to gangliosides almost irreversibly and antibody is not effective once it is bound
What is the role of the hemolysin toxin released by Clostridium tetani?
it produces local necrosis and thereby stimulates the growth of the organism
What is the role of the non-spasmogenic toxin released by Clostridium tetani?
it binds to the neuromuscular junction and is responsible for overstimulation of the peripheral nervous system
What is the pathogenesis of a Clostridium tetani infection?
The organism enters wounds or other tissue sites that have a low oxygen tension. These areas can include the umbilical stump and the uterus of post-parturient females. Deep wounds usually are inoculated with contaminating bacteria which cause necrosis in the surrounding tissues, reduce oxygen tension and thereby the Eh, and allow the germnination and growth of C. tetani
What are the two routes by which Clostridium tetani is spread?
Along peripheral nerves and hematogenous and through lymph
Describe Clostridium tetani’s spread along peripheral nerves.
This is termed ascending tetanus and first affects those nerves closest to the lesion - less common route
Describe Clostridium tetani’s hematogenous spread and spread through lymph.
This is termed as descending tetanus. The nerves affected first are those that are most sensitive to the effects of the toxin.
This is common in horses and humans.
What species are typically affected by Clostridium tetani?
horses, humans, lambs, calves, and others