Pathogenic micro.txt

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Anonymous
ID:
534
Filename:
Pathogenic micro.txt
Updated:
2009-10-26 13:06:35
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Enterobacteriea
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part 2
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  1. what is the systemic manifestation of gram negative?
    Toxic shock ( it needs high bacterial burden)
  2. what is generally initiated by LPS and endotoxin?
    • activation of complement
    • release of cytokines
    • fever
    • decrease in peripheral circulation
    • shock and death
  3. what does septic shock cause?
    • Fever
    • hypotension
    • DIC
  4. what are some factors associated with pathogenesis of enterobacteriae?
    • Endotoxin/LPS
    • Exotoxin ( not in opportunistic E.coli)
    • > Stx-1,2 ( shiga toxin)
    • > LT 1 ( like chlorea toxin)
    • specific virulence factors for other pathogenic members
  5. what types of infections do entrobacteriae group cause generally?
    • Urinary tract
    • wound infection
    • pneumonia
    • memnigitis
    • septecemia
    • gasterointestinal disorder
  6. what is the difference between opportunistic and pathogenic?
    • opportunistic are usually part of normal microflora ( escherchia/ klebsiella)
    • pathogenic are not ( shigella, salmonella, yersenia, and some escherchia)
  7. Neonatal meningitis :
    • E.coli and group B strep cause majority of CNS infection in < 1 month infants
    • 75% E.coli are K-1 serotype
    • EC-k-1 is commonly presented in GI tract of pregnant woman
    • immediate treatment of infant with IV antibiotic ( penicilin and aminoglycoside)
  8. what is gasteroenteritis by E.coli defined by?
    it is defined by serotype of e.coli not a part of common microflora
  9. how many strains are there causing gasteroenteritis:
    • EPEC
    • ETEC
    • STEC=EHEC
    • EIEC
    • EAEC
  10. Some characteristics of EPEC strain are:
    • uncommon in Us
    • Cause watery diarrhea in infants
    • cause A/E lesions similar to STEC
  11. what are some virulence factors associated with EPEC?
    • BFp bundel forming pili
    • TTSS
    • Intimin ( adhessin)
    • TIR ( equivalent unknown for STEC)
  12. Some of characteristic of ETEC are:
    • very common in developing countries ( mostly infants and travelers )
    • Infection via ingestion of contaminated food and water
  13. what are some symptoms associated with ETEC?
    watery diarrhea , cramp vomit, develope after 1.2 days and persist for 3.4 days
  14. what are some virulence factors associated with ETEC?
    • Heat stable and labile
    • exotoxin stimulate hypersecretion of fluids and electrolytes.
    • both toxins are A-B subunit toxins
    • either toxin sufficient to cause symptoms
    • fimbreae which is important for adherence
  15. what are some ways to treat ETEC
    • Cook , boil and peel
    • water and electrolytes
  16. some characteristics associated with EHEC and STEC
    • most common in developed countries
    • more than 50 serotypes and most common in STEC o157:h7
    • cause bloody diarrhea
  17. what are some ways of transmission EHEC=STEC
    • low infection dose ( less than 100)
    • most common during warm days in children under 5
    • contaminated , undercooked meat and raw vegetables
  18. Disease associated with EHEC= STEC
    • severity varies
    • uncomplicated diarrhea to hemorrhagic colitis
    • initial watery ( 3.4 days)
    • in young children severe complication
  19. what is hemolytic uremic syndrome associated with
    • it is associated with shiga toxin 2 producing strain
    • acute renal failure leading to death
  20. what are some virulence factors associated with STEC/EHEC
    • they induce A/E lesions as do EPEC
    • Expression of shigella toxin 1 and 2
    • Toxin acquired by bacteriophage
    • toxin binds to receptor found on endothelial cells of intestine and kidneys
    • induce cell death ( inhibition of protein synthesis)
    • isoform of Slt2 binds preferentially to renal endothelial and associated with HUS
  21. what are some diagnostic ways for EHEC
    • most o157 don't ferment sorbitol ( sorbitol mcConkey is used for stool samples)
    • ** there is a drawback since some ferment sorbitol and also this method does not assess toxin production
    • prefered method
    • stool sample on mcConkey and analyze colonies for toxin production ( PCR)
  22. what are treatments for EHEC?
    • water and electrolytes for treating symptoms
    • antibiotic not recommended since it may prolong the disease
    • cook meat
    • wash, boil, cook and peel

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