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30 Cards in this Set
- Front
- Back
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C.difficile transmission
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spore former
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Microbio of C. difficile
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Gram+ rod, spore former, part of human microflora, use an A-B toxin
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Air usage of C. difficile
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Anaerobic
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Why is C. difficile important in industrialized countries?
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-Can survive as spores
-Antibiotics drive this -Most common diarrheal disease require specific antimicrobial interventions |
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In which age range is C. difficile most prevalent?
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>65yo
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What has driven re-emergence of C. difficile?
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-Improved lab diagnosis
-Aging population -Inc use of antimicrobials, especially fluoroquinolones w/anti-anaerobic activity, to which Cdiff is resistant |
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Keys to pathogenesis of Cdiff
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When anaerobic gut flora are present, Cdiff resistant.
Altered gut flora creates permissive environment. Spores present or obtained can start colony -susceptible for up to 6 weeks after antimicrobials Grows and produces toxin A and B Toxins bind and come in via receptor mediated endocytosis Toxins inactivate small GTPase |
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C.difficile intestinal response
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pseudomembranous colitis
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Spectrum of disease of Cdiff
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asymptomatic
mild diarrhea profuse diarrhea w/non-specific colitis pseudomembranous colitis toxic megacolon |
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New pandemic of Cdiff?
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NAP1
-has mutation in specific gene which down-regulates toxin production during log phase (growth) -results in 20-fold inc of toxin production (during stationary phase) |
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Lab dx of Cdiff
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-Stool screen for glutamate dehydrogenase, if positive, screen for gene with PCR (GDH test is sensitive, but modest specificity, good screen)
-Run PCR for toxin genes |
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Rules for Cdiff testing.
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-If stick stands, the test is banned.
-If stick falls, test them all. |
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Tx for Cdiff
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Vancomycin po, tapered dosing to kill spores may be used
Metronidazole was drug of choice, concerns of high relapse. Fidaxomicin is new, but very expensive |
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Hand cleaning for Cdiff patients
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soap and water, not alcohol
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Difference in botulism and tetanus paralysis
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Flaccid in botulism, spastic in tetanus
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Cause of botulism and tetanus
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Activity of protein exotoxins produced by C. botulinum and C. tetani
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Sources of botulism toxins
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honey, canned foods, black tar heroin, bioterrorism
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Most common form of botulism
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infant botulism
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Why is honey associated disease much more common in US?
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Recommendations by AAP
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How is toxin transported to infants?
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Time of weaning, toxin absorbed from gut into bloodstream; presents with constipation, poor suck, weak cry
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Describe presentation of wound botulism
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-Skin popping
-Organism enters and produces toxin -Cosmetic Botox |
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Describe presentation of food-borne botulism.
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Ingestion of pre-formed toxin, outbreaks limited to family members
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What makes botulism a good weapon?
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High lethality, isolated easily from soil, released as aerosol, inhalation botulism
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Botulism pathogenesis
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Inactivates SNARE proteins, necessary for acetylcholine
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Presentation of botulism
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Blurred, muscle weakness, drooping eyelids, slurred speech, difficulty swallowing, patient is afebrile and alert
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When is botulism antitoxin actually administered?
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Early, effects are irreversible
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Why is tetanus pretty much eliminated?
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Tetanus vaccine (every 10 years)
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Common population of tetanus
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Between 25-59 without boosters
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Concerns for tetanus
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Following trauma/catastrophic events
Childbirth |
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Pathogenesis of tetanus
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Inactivates synaptobrevin, which inhibits normal post synaptic inhibition
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