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2011-03-02 23:52:40
Lab test

Lab test
Show Answers:

  1. What color is fresh MSA agar?
    Transparent and pink
  2. What does MSA medium select for?
    Staphylococci, growth of other organisms are inhibited by the salt.
  3. How does MSA differentiate between pathogenic and non-pathogenic staphylococci?
    Pathogenic species cause the agar to change from pink to yellow.
  4. What does poor or no growth of MSa mean?
    Not staphylococcus
  5. What color is fresh CNA agar?
    The same color as normal agar.
  6. What does growth on CNA mean?
    Gram positive cocci.
  7. What is added to Startch agar to read the results?
  8. What does fresh bile esculin agar look like?
    pale yellow/green color.
  9. What does a color change in bile esculin agar mean and what color?
    Presumptive identification of Enterococcus with black color change in the medium.
  10. What does coagulation mean in the Coagulase test?
    positive for pathogenic staph.
  11. What does the Catalase test for?
    Gas production. If it is generated the organism is aerobic.
  12. Is the MacConkey agar selective or differential?
  13. What does MacConkey agar look like fresh?
    transparent and pale purple in color.
  14. What does MacConkey agar differentiate between?
    coliform and non-coliform bacteria
  15. What does a positive test in the MacConkey agar look like?
    Color change to pink/red without bile precipitate.
  16. What color is HE agar fresh?
    transparent and greenish/brown in color.
  17. What does HE agar select for growth?
    Gram negative
  18. What does a color change to orage mean in HE agar?
    Not Shigella or Salmonella
  19. What does a color chage to blue-green with black precipitate mean in HE agar?
    possible Salmonella
  20. What does a blue-green growth without black precipitate mean in HE agar?
    Possible Shigella or Salmonella.
  21. What color is fresh MR agar?
    transparent straw color
  22. What does it mean when MR broth turns red?
    Mixed acid fermentation occurs
  23. What color is fresh PR broth?
    transparent red
  24. What color is fresh Sim agar?
  25. What color is positive for Sim agar?
  26. What do you add to Phenylalanie agar to show results?
    10% ferric chloride
  27. What color change would you see in Phenylalanine agar for a positve result?
  28. What color is fresh TSI agar?
    transparent peach colored
  29. What do you ad to Sim agar to see results?
    Kovac's reagent
  30. What does black in the sim's agar mean
    sulfur is produced