Infections of the Nervous System II (11) Flashcards
How are tetanus and botulism similar?
both are caused by organisms in the genus clostridium
both affect the nervous system
both produce potent exotoxins
What are the characteristic clinical signs of tetanus? Where?
spasmodic, tonic muscular contractions
CNS
What are the characteristic clinical signs of botulism? Where?
flaccid paralysis
neuromuscular junction
What are the properties of Clostridium spp.?
gram-positive
obligate anerobic
spore-forming rods
What is the bacteria causing tetanus?
Clostridium tetani
What is the bacteria causing botulism?
Clostridium botulinum
What is tetanus caused by?
a neurotoxin produced by Clostridium tetani
Where is clostridium tetani found?
in soil and transiently in intestinal tracts
usually introduced into tissues through deep puncture wounds
How does clostridium tetani enter the body?
deep puncture wounds
The neurotoxin in tetanus causes _____
generalized muscular spastic paralysis
Clostridium tetani is an obligate [aerobe/anaerobe]. What does it lack?
anaerobe
oxidase and superoxide dismutase - susceptible to oxygen *requires oxygen-free environment to grow
What is the appearance of clostridium tetani?
drum-stick appearance - gram-positive
How does C. tetani enter the host? What does it need specifically?
deep penetrating wounds
it is unable to grow in healthy tissue or even in wounds if the tissue remains at the normal oxidation-reduction potential of the circulating blood
TISSUE NECROSIS
What is another contributing factor to C. tetani entering the host?
contamination with a facultative anaerobic bacteria - results in reduced oxygen - help in bacterial replication = toxin production
What is tetanospasmin? It causes ________. How?
causes spasmodic, tonic contractions of the voluntary muscles by interfering with the release of inhibitory neurotransmitters from presynaptic nerve endings
What happens if more tetanus toxin is released at the site of infection than the surrounding nerves can take up?
excess is carried off by the lymph to the bloodstream
& thus to the CNS where it causes descending tetanus
What are the spread/effects of tetanus toxin? (tetanospasmin)
A dog presented with muscle stiffness in this characteristic stance. What is likely the cause?
clostridium tetani
Which species is generally resistant to tetanus? Most sensitive?
birds
horses and lambs
How do you diagnose tetanus?
anaerobic culture
How do you treat tetanus?
antitoxin
toxoid
What does botulism form that can remain dormant for extended periods causing repeated exposure?
spores
Who is most susceptible to clostridium botulinum? Least?
water birds
pigs
What is botulism an example of?
a disease often mediated by bacterial exotoxin
NOT by the bacteria itself
How is botulism different from tetanus regarding entry?
c. botulinum does not necessarily have to enter the host - the exotoxin is sufficient
What is toxicoinfectious botulism?
bacteria multiply in the intestinal tract, possibly in superficial necrotic areas such as ulcers
produce toxin which is absorbed systemically
What ar example of toxicoinfectious botulism?
floppy baby syndrome
shaker foal syndrome or wound botulism
At the neuromuscular junction, blocking acetylcholine reals at the neuromuscular junction at peripheral nerve endings leads to _____
flaccid paralysis
T/F: Bacterial isolation for botulism is critical
FALSE - of limited value
What is important in diagnosing botulism?
exotoxin identification
What is the toxin neutralization test in mice regarding botulism? It has a characteristic ____
intravenous inoculated with serum containing toxin
wasp-waist appearance
If the initial neutralization assay is positive for botulism, what else should be done?
toxin typing assay
What is the limit of antitoxins?
only inactivates toxin not bound
What is treatment/prevention for botulism?
antitoxin
antibiotics
supportive care
immunization with toxoid vaccine
