lab 9

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Neilgal
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270477
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lab 9
Updated:
2014-04-27 19:54:26
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biol251
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biol 251 lab 9
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  1. Drinkable water
    Portable
  2. What are the sources of fecal contamination?
    water source stars at mountain picks to revers that mixed with washes. All of these sources are exposed to human/animal fecal contamination and other pollutants.
  3. coliforms
    • All enterobacterceae
    • All ferment lactose
    • All gram negative rods
    • All anaerobe facultatives
    • All produce gas
  4. What does coliforms and non-coliforms of fecal contamination have in common?
    • They all cause GI tract infections
    • diarrhea, dysentery, and vomiting.
  5. Why the media we used in lab 8 is selective media
    Because it inhibit the growth of gram positive bacteria and select the growth of gram negative
  6. Why is the media we used in lab 8 is deferential media
    It differentiate between lactose fermenting coliforms from other gram negative that do not ferment lactose.
  7. Water screening test
    • A quick test of coliforms in 100 mL of water.
    • The water will change color blue/green and participials will glow under 360 nm UV light if coliforms are present
  8. Why is Eosin methylene blue (EMB) is a deferential media?
  9. Lactose frequenters produce acid:
    • E. coli produce a lot of acid turn media color green shean
    • Other lactose fermenters produce less acid turn the media pink to red/purple
  10. Why is Eosin methylene blue (EMB) is a selective media?
    • Because it selects gram negative growth only
    • Some dyes in this media inhibit gram +
  11. EHA Media (Hektoen Enteric agar)
    • Selective: Contains bile salt that inhibits G+
    • Deferential:
    • E. coli turn agar color to pink, yellow or orange
    • Shigella: blue green
    • Salmonella produce H2S black
  12. MCA (MacConkey agar)
    • Selective: Bile salt & crystal violet inhibit G+
    • Differential:
    • Lactose frementer turn media pink.
  13. Define and list characteristics of coliforms.  Why is water tested for coliforms?
    • Members of enterobactriaceae, facultative anaerobes, produce gas, ferment lactose.
    • Because they can cause GI tract infections
  14. Name three diseases spread through water.
    Dysentery, diarrhea, and vomiting, cholera
  15. Staphylococcus aureus
    • Grow form:  cluster
    • Colony color: Golden yellow
    • Catalase test: positive
    • Infection: MRSA (Methicillin resistance staphylococcus aureus)

  16. Enterococcus
    • Growth form: Chains
    • Colony color: white
    • Catalase test: negative
    • Infection: VRE (vancomycin resistance enterococcus)
  17. Catalase
    Enzyme produced by Staphylococcus that break down oxygen radicals
  18. Staphylococcus in general
    • halotolorant
    • normal residents of the body
    • opportunists can become pathogenic under certain conditions
  19. Mannitol salt plate
    Mannitol is used as sugar

    • Differential media : Because it will turn yellow if mannitol is fermented (S. saprophyticus & S. aureus)
    • Selective media: because it selects for only halotolorant bacteria
  20. What are S aureus, S. saprophyticus and S. epidermis have in common?
    What differentiate between them?
    • All are halotolorant
    • S. epidermis; cause (endocarditis inflammation of the heart lining), Cannot ferment mannitol
    • S. saprophyticus cause UT infection,
    • S, aureus: cause MRSA,
  21. (BAP) Blood agar plate
    • S.epidermis: gamma hemolysis (non hemolysis)
    • S. saprophyticus : gamma hemolysis
    • S. aureus: Beta hemolysis (complete hemolysis)

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