BacT Lab Flash.txt

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BacT Lab Flash.txt
2011-03-27 21:30:22
BacT Lab Final

BacT Lab Final
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  1. *What disinfectant do we use in the lab?
  2. T/F BSL-1 agents are known to cause disease in healthy humans.
  3. How should petri plates with bacterial cultures be incubated? (What position?)
    Inverted (upside down)
  4. Give one example of BSL-1 agent:
    E. Coli
  5. GIve one example of a BSL-2 agent:
    Salmonella, HIV, Lyme Disease (Borrelia Borgderferi)
  6. Give one example of a BSL-3 agent:
    Mycobacterium TB, BAcillus anthracis, Chlamydophila psittici
  7. Give one example of a BSL-4 agent:
    Samllpox, Ebola virus
  8. What is the significance of a gram stain?
    • Bacterial Identification
    • Antimicrobial selection
    • May provide treatment information
    • Clinical evaluation of disease
  9. *Gram Stain Procedure
    • 1. Crystal Violet/ Wash (Gram + Stain)
    • 2. Iodine/ Wash (Mordant)
    • 3. Alcohol/ Wash (Decolorizer- removes cv from gram -))
    • 4. Safranin/ Wash (Stains gram -, counterstain)
  10. What is the most important step of the gram stain?
    Decolorizing (for distinguishing the gram- from gram +)
  11. *What are some complications with gram stains the are possible?
    • Poor Prep. (over-heating, too thick a smear)
    • Poor washing
    • Old Sample
    • Decolorize too long
  12. What are the three shapes of bacteria?
    Cocci, Rods and Spiral
  13. What would describe cocci in chains?
  14. What would describe cocci in clumps?
  15. *What is the reagent for the KOH test?
    3% Potassium Hydroxide
  16. What is the purpose of the KOH test?
    To differentiate gram + from gram -
  17. What is a positive KOH test?
    When the liquid becomes viscous from the lysis of a gram - cell wall liberating nucleic acid
  18. What is a streak plate useful for?
    It is good for isolating bacteria
  19. What is a pour plate useful for?
    It is more for quantification and accuracy
  20. What is a spread plate useful for?
    It is good for quantification. It is more convenient than pour and there is less contamination.
  21. What two plate methods are good for quantification?
    Pour and Spread
  22. T/F Phase contrast microscopes can show living cells
    True- and bright field as well
  23. *T/F Oil immersion lens helps to increase focus?
    False- RESOLUTION!
  24. T/F Enriched Nonselective media does not contain inhibitors.
  25. List a few Enriched Nonselective Media:
    • Blood agar (also differential)
    • Trypticase soy agar or broth
    • Mueller-Hinton agar- Anti-microbial inhibiiton assay
    • Thioglycollate broth
    • Sabouraud Dextrose agar- isolates fungi
  26. Sabouraud's dextrose is best for:
    Fungal isolation
  27. Mueller-Hinton agar is best for:
    Antimicrobial testing
  28. Define Selective Media:
    Supporting the growth of specific bacteria while inhibiting growth of others.
  29. Examples of selective Media:
    • (MEMXL)
    • MacConkey agar (also differential) Best for Gram - bacteria
    • Eosin-Methylene blue agar (Also differential)
    • Mannitol salt agar (also differential)
    • Xylosine lysine deoxycholate (XLD)
    • Lowenstein-Jensen medium
  30. What is differential medium?
    Contains substances like blood or acid-base indicator that only certain microorganisms will respond to in a characteristic way (ex: E. Coli on Eosin methylene blue agar= shiny green)
  31. Name some differential mediums
    • Blood agar
    • MacConkey
    • Eosin-methylene blue
    • Mannitol Salt
    • Urease Broth
  32. What type of blood is in blood agar?
    5% Sheep blood (Can have horse and Bovine too)
  33. What type of hemolysis do you see with alpha, beta and gamma hemolysis?
    • alpha- partial
    • beta- complete
    • gamma- no hemolysis
  34. Alpha hemolysin causes what type of hemolysis?
    Beta hemolysis
  35. Beta hemolysin causes what type of hemolysis?
    Alpha hemolysis
  36. What types of inhibitors are in selective media?
    Antibiotics, chemicals and dyes
  37. What inhibits Gram + on MacConkey agar?
    0.5% bile salts and crystal violet
  38. How does MacConkey express lactose fermentation? Using what pH indicator?
    Color change from light pink medium to dark red. The pH indicator is neutral red and acid production will change the color when pH falls below 6.8
  39. Describe the colors for acid and alkaline presentation with Phenol red:
    • Acidic= yellow
    • Basic= Red
  40. Describe the colors for acid and alkaline presentation with Neutral Red:
    • Acidic= Red
    • Basic= Yellow
  41. Catalse is present in ________________:
    Most aerobic bacteria but not in obligate anaerobes.
  42. What is the purpose of the Catalse test:
    To test for the presence of the enzyme catalos which indicates either aerobic or facultative aerobic bacteria.
  43. *What reagent is used in the catalase test? What is the reaction?
    • H2O2.
    • Catalase converts 2H2O2 to 2H2O + O2
  44. A positive catalase test will show:
  45. What is the purpose of the oxidase test?
    To detect cytochrome oxidase. Cytochrome oxidase is an enzyme used in some bacteria to convert oxygen to water molecules in the electron transport chain to ultimately generate ATP.
  46. *What reagent is used in the oxidase test?
    Kovac's reagent
  47. What will you see in a positive Oxidase test?
    Filter paper will change to a blueish/purple color
  48. Cytochrome oxidase is mainly present in:
    Aerobic gram - bacteria
  49. *How much bacteria is in a 0.5 McFarland Test?
    1.2 x 10^8 CFU/ml
  50. What is another name for the Anitmicrobial susceptibility test?
    Kirby-Bauer test
  51. TSI stands for:
    Triple sugar Iron
  52. TSI inoculation can tell you what three things?
    • Sugar fermentation
    • Gas production
    • H2S production
  53. When will a pH change occur in microbial testing?
    • If there is fermentation
    • If amino acids are utilized
    • If urea is utilized
  54. Carboxylation will increase or decrease pH?
    Increase (more basic)
  55. Deamination will increase or decrease pH?
    Decrease (more acidic)
  56. What are the components of triple sugar iron tests?
    • 0.1% Glucose
    • 1% Lactose
    • 1% Sucrose
    • Phenol Red (acid = yellow)
    • Ferrous Ammonium Sulfate (H2S production + ferrous sulfate = black)
  57. What is the purpose of the urease test?
    Urease hydrolyzes urea to ammonia and CO2. If ammonia is produced, the pH indicator phenol red will turn the urease broth red as it becomes more alkaline.
  58. How is a TSI test recorded? Slant/Butt or Butt/Salnt?
  59. Mannitol Salt Agar is used best for which bacteria? What is the pH indicator?
    Used to grow Staphylococcus spp. and phenol red is the indicator.
  60. What Staph species shows yellow colonies on Mannitol Salt Agar? What Staph. spp. shows white colonies?
    • Staph. aureus= yellow
    • Staph. epidermidis= white
  61. What percentage of NaCL is in Mannitol Salt Agar?
  62. In the Motility and Ornithine Decarboxylase test, what has happened if the medium turns purple?
    Decarboxylation of ornithine has taken place and increased the pH (alkalinized)
  63. Ornithine is decarboxylated into what?
    • Putrescine
    • Onithine to putrescine gives purple color
  64. Indole is formed by what process?
    Trytophan to indolepyruvic acid to indole
  65. What color is indole on the MOI test?
    Red (with the use of Kovac's reagent)
  66. What does XLD stand for?
    Xylose Lysine Deoxycholate
  67. With Eosin Methylene Blue agar, how does E. Coli look?
    • Shiny metallic green whit black surrounding.
    • Black= fermentation.
    • Methylene blue is used to inhibit gram + growth.
    • Eosin is the pH indicator.
  68. What is the inhibitor in XLD?
    Sodium deoxycholate
  69. What are the sugars in XLD?
    xylose, lactose and sucrose
  70. What is the pH indicator in XLD?
    Phenol red
  71. What amino acid is in XLD? What is it's significance?
    • Lysine.
    • Decarboxylation of lysine will increase the pH and turn it dark red. Ex: Shigella spp.
  72. What does salmonella look like on XLD?
    • orange to black
    • Fermentation of xylose decreases pH but decarboxylation of lysine increase pH.
    • Production of H2S = black
  73. What do E. Coli and Klebsiella look like on XLD?
    There is enough sugar so that there isn't a pH change. Same color
  74. Motility and Ornithine Decarboxylase are useful for what?
    Differentiating Enterobacteriacea
  75. As a pH indicator, Eosin turns what color when acidified?
  76. A red slant and yellow butt means what?
    Glucose fermentation
  77. Slant and butt are yellow:
    Fermentation of glucose and sucrose and/or lactose
  78. Gas bubbles in butt and medium split implies:
    Gas production
  79. If the butt shows black, there was:
    H2S production
  80. If the slant and butt red throughout, it implies:
    Nothing fermented
  81. What are some general characteristics of Enterobacteriacae?
    • Gram - bacilli
    • Cytochrome Oxidase neg.
    • Grow on MacConkey Agar
    • Lactose fermenters
  82. How many biochemical tests are there in the REMEL MICRO-ID?
  83. *Why do we use Meuller-Hinton Agar for antibody disk diffusion?
    Because it doesn't interfere with the antibacterial disks. No false +'s or -'s unlike using MacConkey or Blood Agar.