1. What genus of bacteria is classified by Lancefield groups?
  2. A positive latex agglutination result in Group A would indicate what organism?
    Streptococcus Pyogenes
  3. S.Pyogenes is the causitive agent of what diseases?
    Bacterial pharyngitis ("strep throat"), impetigo, scarlet fever, necrotizing fascitis, TSS.
  4. How are S.Pyogenes infections treated?
  5. What type of bacteria are identified by the Enterotube test?
    Enteric bacteria
  6. What are some characteristics of enterobacteriacea?
    Gram negative, Catalase positive, Oxidase negative, Facultative anerobes.
  7. What dyes are used in EMB Agar?
    Eosin y & Methylene Blue
  8. True or False:

    EMB Agar inhibits the growth of gram negative bacteria
  9. What is the EMB Agar test used to identify?
    Fecal Coliforms
  10. Why is a Nutrient Agar plate used along with the EMB Agar plate?
    To demonstrate a comparison for growth, or to show how well gram positive growth was inhibited.
  11. What color on EMB would indicate a possible coliform?
  12. What color on EMB would indicate a probable coliform?
    Dark purple to green or black.
  13. How is EMB Agar selective?
    It inhibits the growth of Gram positive organisms.
  14. How is EMB Agar differential?
    It reacts with lactose fermentors to change the color of the agar.
  15. Beta Hemolysis
    Complete hemolysis of RBC's
  16. Alpha hemolysis
    Partial Hemolysis of RBC's
  17. Gamma Hemolysis
    No hemolysis of RBC's
  18. A clearing around the colonies would indicate which type of hemolysis?
    Beta hemolysis
  19. A green discoloration of the blood agar would indicate which type of hemolysis?
    Alpha hemolysis
  20. What are hemolysins?
    Gram positive cocci toxins that destroy red blood cells.
  21. Why is the streak-stab technique prefered in Blood Agar?
    It provides a favorable enviroment for streptolysins.
  22. Streptococcus Pyogenes demonstrates what type of hemolysis?
    Beta hemolysis
  23. Streptococcus Pneumoniae demonstrates what type of hemolysis?
    Alpha hemolysis
  24. Streptococcus Pneumoniae is the causitive agent of what diseases?
    Cellulitis, brain abcesses, endocarditis, septic arthritis.
  25. In blood agar, why is it important to cover and tape the plates before incubation?
    After incubation, the number of bacteria increase and pose a greater risk of infecting people in the lab.
  26. Why is the streak plate method preferred over the spot inoculation in blood agar?
    Because the sample from the throat is not a pure culture, so isolation is needed to identify the individual colonies.
  27. What indicator is used in MSA agar? How does it react to changes in PH?
    Phenol red; turns yellow in acidic conditions and pink in alkaline conditions.
  28. How is MSA agar selective?
    Its high salt content inhibits the growth of most other bacteria except gram positive staphylococci.
  29. How is MSA agar differential?
    Mannitol provides a substrate for fermentation, the media will change color with acidic conditions.
  30. MSA is used for isolation and differentation of what staphylococcus organism?
  31. Why does E.Coli not grow well on MSA?
    MSA inhibits the growth of most gram negative bacteria.
  32. Why is a known catalase positive organism used in the catalase test?
    To verify the quality of the peroxide.
  33. What is the purpose of adding hydrogen peroxide to an uninoculated tube for the catalase test?
    It provides a comparison in the case of minimal reaction.
  34. What blood type is considered a universal donor?
    O negative
  35. What type of blood is considered a universal recipient?
    AB positive
Card Set
Lab Practical