Microbiology Midterm

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79 Terms

1
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<1mm colony size is considered…

pinpoint

2
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1-2mm colony size is considered

small

3
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2-3mm colony size is considered

medium

4
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>3mm colony size is considered

large

5
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transparent colony means it is

clear

6
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translucent colony means it is

nearly clear

7
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a frosted appearance to a colony is considered

opaque

8
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an iridescent colony means

it changes color as the plate is tilted

9
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what is an example of a bacteria whose colonies are iridescent

pseudomonas aeruginosa

10
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what does it mean for a colony to be butyrous

buttery consistency

11
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what does it mean for a colony to be friable

it is brittle and falls apart

12
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what does it mean for a colony to be viscous

it sticks to the loop

13
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what does it mean for a colony to be mucoid

it is slimy and strings from the loop

14
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what is beta hemolysis

clear halo around the colony

15
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what is alpha hemolysis

green halo around the colony

16
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what is gamma hemolysis

no hemolysis

17
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what color is MAC lactose fermenter

pink

18
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what color is MAC non lactose fermenter

yellow or no color

19
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what bacteria is known for smelling like grapes

pseudomonas aeruginosa

20
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what bacteria is known for smelling like bleach

Eikenella corrodens

21
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what is a direct gram stain

stained bacteria taken directly from the colony

22
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what is an indirect gram stain

stained bacteria that comes from a plate after growth

23
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what kind of media should you not take bacteria from for an indirect gram stain

selective

24
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fixing a slide ensures

  • all vegetative organisms are killed

  • preservation of the bacteria from changes

  • improved adhesion to the slide

  • improved penetration of the stain into the cell wall

25
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what is the best way to fix a slide

flooding the slide for 1 minute with 95% methanol

26
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flooding the slide with 95% methanol is best for

  • preserving cell morphology

  • best for morphology of WBC, RBC and epithelial cells

  • best for bloody specimens

27
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what is a simple stain

one dye or stain is used so everything on the smear is stained the same

28
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what is an example of a simple stain

methylene blue

29
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what is a downside of using simple stain

we can only determine the cell shape

30
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what is differential stain

separates bacteria into different groups depending on staining properties

31
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examples of differential stains include

Gram stain , Acid Fast stain

32
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what is acid fast stain used for

to demonstrate bacteria with mycolic acids in the cell wall

33
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gram stains on acid fast bacteria are either…

gram positive, gram ghosts or gram neutral

34
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What kind of stain in Ziehl-Neelsen

acid fast

35
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what makes Ziehl-Neelsen stain different from Kinyoun

ZN requires heat where Kinyoun does not

36
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what do positive acid fast bacteria look like after staining with Ziehl-Neelsen

red bacteria with a blue background

37
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what is the counter stain for Ziehl-Neelsen

methylene blue or malachite green

38
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how is kinyoun different from Ziehl-Neelsen

has a higher phenol concentration

39
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what kind of stain is Kinyoun

acid fast

40
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what kind of stain is Auramine rhodamine

acid fast

41
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what kind of stain is Acridine orange

special

42
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what does acridine orange stain for

binds non specifically with nucleic acids

43
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what can acridine orange detect

mycoplasma

44
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what kind of stain is auramine-rhodamine

special

45
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what does auramine-rhodamine stain for

binds non specifically to mycobacteria

46
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what kind of stain is Calcofluor white

special

47
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what does calcofluor white stain for

direct detection of fungus

48
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what kind of stain is immunofluorescence

special

49
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what does immunofluorescence stain for

antibody/antigen attachment

50
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what bacteria is immunofluorescence good for

chlamydia trachomatis

51
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what does dark field microscopy detect

spirochetes such as treponema pallidum

52
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what are wet mounts

where microbes are visualized in a living state to see motility

53
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what are negative stains

the background of the smear is colored instead of the bacteria

54
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what is used in negative stains

India ink

55
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what is a bacteria that uses negative staining

cryptococcus neoformans in CSF

56
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What can not be detected with a gram stain

intracellular pathogens

57
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can not be detected by a gram stain

organisms without a cell wall

58
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what can not be detected by a gram stain

organisms with insufficient dimensions to be resolved

59
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what is an example of a bacteria that is an intracellular pathogen

chlamydia spp.

60
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what is an example of a bacteria without a cell wall

mycoplasma spp.

61
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what is an example of an organism with insufficient dimensions to be resolved

spirochetes

62
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what is the primary stain in a gram stain

crystal violet

63
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what is a trapping agent in a gram stain

bonds alkaline dye to the cell wall

64
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what is an example of a trapping agent in a gram stain

Gram’s or Lugols iodine

65
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what is an example of a decolorizer in a gram stain

acetone and/or alcohol

66
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what is the most important step during the gram stain process

decolorizer

67
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what is the secondary stain in the gram stain

safranin - neutral red

68
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a direct gram stain can not be performed on

feces

69
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you can not perform a direct gram stain on

throat swabs

70
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direct gram stains can not be performed on

nasopharyngeal specimens

71
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what causes the crystal violet stain to run out of gram negative organisms

higher lipid content in the cell wall making them more porous

72
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what causes crystal violet to be trapped in gram positive organisms

thicker cell walls

73
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over decolorization causes gram positive organisms to

lose crystal violet stain and appear red/pink

74
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under decolorization causes gram negative organisms to

not have crystal violet removed resulting in a purple appearence

75
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when observing cells under a direct gram stain, phagocytes are an indicator of

inflammation

76
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when observing cells under a direct gram stain, epithelial cells are an indicator of

possible contamination

77
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do you see host cells in an indirect gram stain

NO

78
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what type of gram stain is recorded, but not reported to the doctor

indirect

79
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gram positive organisms will appear pink if

  • cell wall is damaged

  • affected by antibiotics

  • old age

  • autolytic enzymes

  • over decolorization