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34 Cards in this Set
- Front
- Back
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What is the gram stain of clostridium, oxygen requirements, and where are they found in the body?
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They are gram positive rods, obligate anaerobes, and can be found in the intestinal tract
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What is an important characteristic of clostridium in terms of reproduction?
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They are able to form spores
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What are the two clostridia that secrete neurotoxins?
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C. botulinum and C. tetani
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Describe the spore of C. botulinum compared with that of C. tetani
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The spores of C. botulinum are subterminal (not quite at the end of the rod) while tetani spores are terminal "drumsticks"
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What is the human serotypes of botulinum toxin?
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A, B E, and F
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How can the botulinum toxin be inactivated?
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It is heat labile, so it can be inactivated by boiling
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From where do the genes for the botulinum toxin come?
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They come from a bacteriophage or a plasmid
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What is the mechanism of the botulinum toxin?
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It prevents the release of acetylcholine at the neuromuscular junction
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What are the two subunits of the botulinum toxin and what does each do?
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The B subunit binds to the gangliosides of neuronal cells and the A subunit (light chain) degrades synaptobrevin and other fusion proteins on acetylcoline containing vesiscles
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What are the three types of disease of clostridium botulinum?
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1) food borne 2) wound 3) infant
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Describe how food-borne botulinum is acquired
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food is contaminated with the botulinum toxin as a result of a prior soil contamination with C. botulinum in susceptible foods (must be anaerobic)
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How does wound botulism occur?
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Contamination of dead tissue with soil containing spores
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How does botulism in infants occur?
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Ingestion of spores in small numbers that germinate in the intestinal tract and replicate and produce the botulinum toxin
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Why do infants readily get botulism?
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Their intestinal flora has not yet matured
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How does the botulinum toxin reach the neuromuscular junction in food-borne botulism?
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It enters the bloodstream and is distributed throughout the body
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When do symptoms of food-borne botulism occur?
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18-36 hours after ingestion with a range of 6-8 days depending on the dose
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What are the early symptoms of food-borne botulinum?
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cranial nerve defects
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What are the late symptoms of food-borne botulism?
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Symmetric descending flaccid paralysis - weakness in the upper extremities followed by the respiratory tract, and then lower extremities
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What helps differentiate food-borne botulism from other illnesses such as Guillane-Barre and myasthenia gravis?
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No fever, sensory abnormalities, or mental status changes
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What are the symptoms wound botulism?
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flaccid paralysis starting at the wound site and then becoming generalized
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What are the symptoms of infant botulism?
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Constipation, weak sucking ability, cranial nerve deficits, and generalized weakness
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How is a diagnosis of botulism made?
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Clinical presentation, particularly cranial nerve involvment
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How is botulism treated?
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Rapid administration of polyvalent A,B,E antitoxin
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What is the function of the tetanus toxin?
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It blocks the release of the neurotransmitter glycine at the inhibitory synapse
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What do the zinc endopeptidase subunits of the botulinum and tetanus toxins have in common?
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They both degrade synaptobrevin
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What is tetanolysin?
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A toxin secreted by C. tetani that results in beta hemolysis and cross reacts with streptolysin O from group A strep
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How is tetanus transmitted?
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Contamination of a wound or dead tissue with soil containing the spores of C. tetani
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What is the incubation period from infection to symptoms in tetanus?
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3-21 days, with an average of 8 days
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Explain how tetanus toxin reaches the CNS
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It travels from the site of infection to the CNS via retrograde intra-axonal transport and not through the blood
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What are two early symptoms of tetani?
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Trismus (lock-jaw) and risus sardonicus (grimace)
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What are opisthonic spasms?
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Muscle spasms that bend the back, head, and neck backward
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How is tetanus treated?
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Passive immunization with antitoxin (human tetanus immunoglobulin) which must be administered immediately in==
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Describe the tetanus vaccination
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It is a part of the DTaP vaccine - diptheria, tetanus, and acellular pertussis
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Who should recieve a tetanus toxoid after obtaining a wound?
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In patients who have had 3 toxoid doses, superficial wounds should receive the booster if it has been 10 years since their last booster; for all other wounds they should receive it if it has been more than 5 years since the last booster; for patients with less than 3 or unknown toxoid doses, they should receive the toxoid for superficial wounds and toxoid plus tetanus immune globulin for all other wounds
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