Pathogenic micro.txt

Card Set Information

Pathogenic micro.txt
2009-10-25 21:56:15
Shigella and Yersinia

Gram Negative
Show Answers:

  1. what are some epidemiological factors associated with shigella?
    • S.flexenei mostly in underdeveloped countries
    • S.sonnei mostly in developed countries
    • Day cares are important setting for outbreak
    • fecal and oral route
    • mostly pediatric
    • low dose required
    • contaminated food
    • no seasonal variance
  2. what are some characteristics associated with shigella?
    • nonmotile
    • lactose negative
    • H2S negative on TSI
    • Grouped according to O antigen
    • Have capsule K antigen
  3. what are some clinical characteristic associated with shigella?
    • might be asymptomatic
    • early onset ( 1-3)
    • Abdomenol cramps
    • Fever
    • Bloody stool
    • self limiting
  4. what are some ways to diagnose shigella?
    • very fragile in vivo
    • culture rectal swab or stool
    • use of selective media (HE, XLD which inhibits gram +)
    • use of biochemical test
    • serology
  5. what is the general mechanism of infection and replication in listeria and shigella?
    Actin base motility
  6. what does shigella toxin do?
    • cleaves 28S rRNA in 60S ribosomal unit
    • disrupts protein synthesis
    • Lead to cell death
  7. what are factors contributing to pathogonicity of shigella?
    • Endotoxin/ lps
    • ttss
    • incasion ( IpaA, B, C,D)
    • entrotoxin ( induces cell death of macrophage and cell to cell spread) also escape from phagosome
    • exotoxin which mediates endothilial damage leading to hemolitic colitis also in some cases hymolytic uremic syndrome
  8. what are some ways to treat shigella?
    • Rehydration
    • antibiotic treatment
    • in vitro suseptibility
    • start with ampicilin/ trimtroprim and sulfometadoxazole
    • treat carriers
    • proper swage disposal
    • proper hygene
    • water chlorinatin
    • there is no vaccine
  9. what are some general characteristics of uersinia
    • short or clumpy rods
    • lactose negative
    • grouped according to O antigen
    • capsular K antigen
  10. what are some routes of transmission in yersinia?
    • host is animal
    • Y. pestis which is mostly found in rodents, this is a vector borne disease transmitted bu bite of flea
    • pulmonary pleauge which is highly infectious , transmitted person to person and it is arosel.
  11. what are some ways of disease manifestation?
    • . bubonic pleauge
    • onset after 2 to 6 days
    • enlarged tender lymph node, fever and chill
    • .septimatic plegue
    • fever, chill, abdominal pain, bleeding into skin and other organs
    • * both of above can lead to pneumonic plegue
  12. what are some treatments for the plegues?
    • chemotherapy ( streptomycin and chloramophonical)
    • avoiding rodants
    • pest control
    • monitoring plegue in rodant population
    • use of insectisides
    • drug treatment
    • no vaccine!!
  13. what mechanism does yersinia use for invasion?
    zipper mechanism
  14. what is the role of YOP in yersinia?
    • it help avoid host cell macrophage
    • YOP H inhibition of phagocytosis
    • YOP J induction of appotosis
  15. what are some factors contribution to pathogenesis of yersinia?
    • Endotoxin/ LPS
    • incasion
    • TTSS
    • YOP
  16. what is enteric yersinia infeciton mostly associated with?
    • intake of contaminated food
    • it is more common in winter
    • zoonotic > pigs
    • mostly in young children
    • 4-7 days after exposure
    • last 1-3 weeks
    • fever, abdominal pain on right side and bloody diarrhea
    • usually self limiting
    • use TMS or aminoglycoside
  17. where and how does Y.enterocolitis grow and what does it cause?
    • it grows at 4C
    • also grows on large scale on contaminated blood sample
    • cause bacteremia after blood transfusion and septic shock