The flashcards below were created by user mnvang321 on FreezingBlue Flashcards.

  1. What is C. diff's method of action?
    -both toxins glucosylate (+ glucose)  a threonine residue on G proteins (which control many cell processes) .

    -control polymerization / depolymerization of actin -pseudopodia etc -- requires constant turnover. 

    • -G protein cycle btwn 2 states. 
    • (bind GDP and GTP mediates effects of protein)
  2. Why are G proteins important?
    • control cell processes 
    • control polymerization/depolymerization of actin -pseudopodia etc - requires constant turnover. 
    • cycles btwn GDP and GTP
  3. Where does the A and B toxin act on the GDP-bound form ?
    the threonine residue (that's exposed to be glucosylated)

    -in GTP form the threonine is buried in protein and inaccessible to toxin
  4. What is the result of action of A and B toxin?
    reduces GTPase activity of protein and increases release of GTP from GTP-bond form (glucosylated-GTP bound form has a lower affinity for GTP)
  5. Control of toxin gene expression
    • tcdA /tcdB toxin genes are located on PaLoc pathogenicity island present in all toxogenic strains.
    • Under the control of regulatory genes tcdC (down) and tcdR (up)
    • Toxin levels highest in late-exponential phase of growth
    • Transcription and expression of tcdR is highest in early exponential phase leading to expression of A and B toxins
    • • When toxins build up to highest level, tcdC is expressed which counters tcdR decreasing the expression of the toxin
    • tremendous energy expenditure - 5% of total protein (in-vitro pure cultures) - very powerful toxins and small amounts can cause severe reactions.
    • What do the bacteria get in return for this
    • Why should there be this control – more toxin the better ???
    • - Nutrients
  6. How do you treat C. diff?
    -replace antibiotic causing problem w/ vancomycin or metronidazole (kills c.diff but doesn't affect norman flora)
  7. How do you prevent C. diff?
    at early diagnosis (antibiotic associated diarrhea), monitor for A & B toxins in feces.
  8. What's an alternative therapy for C.diff?
    -replace resident flora using enema containing dilute feces 4rm fam. member.

    (use fecal bacteriotherapy/ fecal micriobiota transplantation (FMT))
  9. What is an enema?
    procedure of introducing liquids into rectum and colon via anus
  10. What are the historical potential reasons for increased CDAD ?
    • changes in underlying host susceptibility 
    • changes in antimicrobial prescribing
  11. What are the recent potential reasons for increased CDAD?
    • new strain w/ increased virulence 
    • (CDT-binary toxin)
    • variations in TcdB activity 
    • changes in infection control practices
  12. What is PulseNet?
    detection of Foodborne Disease by Pulsed-Field Electrophoresis (PFGE)
  13. What organisms are made up of spirochetes?
    Treponema pallium & syphilis
  14. What are the characterisitics of spirochetes?
    • Gram (-)
    • Thin helical
    • Motile, corkscrew style of movement
    • Internal flagella
  15. What are organisms that are spirochetes?
    • Borrelia burgdorferi - Lyme Disease 
    • Treponema pallidum - Syphilis
  16. What is the morphology of spirochetes?
    Peptidoglycan btwn 2 membranes
  17. What is the physiology and motility of spirochetes?
    • has a protoplasmic cylinder
    • 1 to many internal flagella emerge 4rm poles (endoflagella)
    • covered by multilayered, flexible membrane (outer sheath)
  18. How does the motility work for spirochetes?
    • endoflagella rotate -protoplasmic cylinder is rigid and outer sheath is flexible. When flagella rotate in same direction, the protoplasmic cylinder rotates in opposite direction. 
    • this tension placed on cell causes flexing, twisting, jerky corkscrew movement. 
    • effective in viscous solution, blood and tissues.
  19. What disease has similar progression to Lyme Disease?
    -Syphilis; both caused by spirochetes (but diff genera)
  20. What do Lyme Disease and Syphilis have in common?
    multiple stages in their life cycles
Card Set
11-16 (C.diff:CDAD and PMC)
Show Answers