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Lab techniques 2 > Specimen Collection and Staining > Flashcards

Specimen Collection and Staining Flashcards

1
Q

Eukaryotic cells

A

Contain genetic material within a membrane (nucleus)

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2
Q

Prokaryotic cells

A

Contain genetic material but does not have a nuclear membrane.

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3
Q

Is bacteria Eukaryotic or Prokaryotic?

A

Prokaryotic

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4
Q

What does presumptive identification mean?

A

“Best guess” on what is growing

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5
Q

What is the process of identifying bacteria?

A
  1. Collect the specimen
  2. Initial Gram stain (Direct or Indirect)
  3. Inoculate culture media
  4. Incubate for 18-24 hours
  5. Check growth. If no growth reincubate and recheck
  6. If positive: select colonies and perform gram staining and continue with ID
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6
Q

What is used to collect samples from hollow organs and external lesions?

A

Aspiration (bladder or pustules)

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7
Q

What samples need to be processed immediately?

A

Swab samples

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8
Q

What should the specimen contain?

A

The organism causing the problem

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9
Q

What should you do to keep yourself safe while working with microbes?

A

Wear gloves, lab coats, and closed toed shoes

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10
Q

Why do we use gram staining?

A

To categorize bacteria, which helps the veterinarian select treatment

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11
Q

What is the first step of the gram staining process

A

Use a wax pencil to draw a circle on the slide

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12
Q

What is the second step of the gram staining process

A

Place distilled or sterile water and the sample in the wax pencil circle

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13
Q

What is the third step of the gram staining process?

A

Air drying

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14
Q

What is the fourth step of the gram staining process

A

Heat fixing

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15
Q

After heat fixing, what do you flood the slide with?

A

Crystal violet

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16
Q

How long do you flood the slide with crystal violet for?

A

30-60 seconds, but read the package insert for exact time

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17
Q

What do you rinse the slide with after letting the crystal violet sit on the slide?

A

Distilled water

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18
Q

What is the next solution that you flood the slide with after you rinse the Crystal violet?

A

Iodine for 30-60 seconds

Rinse with distilled water after

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19
Q

What is the the next solution you flood the gram slide with after rinsing the Iodine?

A

Decolorizer for 10 seconds until no more color washes off and then rinse with distilled water

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20
Q

What is the final solution you rinse the gram stain slide with?

A

Safranin for 30-60 seconds.

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21
Q

The primary stain is usually what?

A

Crystal violet

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22
Q

What is the the mordant stain and what does it usually do?

A

Gram’s Iodine solution and it fixes dyes to the cell wall

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23
Q

What is the Decolorizer?

A

95% ethanol or acetone

24
Q

What is the Counterstain?

A

Basic fuchsin or safranin

25
Q

Gram positive bacteria contain what percentage of peptidoglycans in the cell wall?

A

60-90%

26
Q

What color do gram positive bacteria turn?

A

Purple.

27
Q

Why do gram positive bacteria turn purple?

A

Because of the high number of peptidoglycans

28
Q

Gram negative bacteria contain what percentage of peptidoglycans in the cell wall?

A

10-20%

29
Q

What color do gram negative bacteria turn?

A

Pink

30
Q

Why do gram negative bacteria turn pink?

A

Because of the low number of peptidoglycans and they lose the crystal- violet with the decolorizer

31
Q

What does Gram variable mean?

A

Gram variable implies that the bacteria will stain both purple and pink but have the same morphology

32
Q

Is Gram variable the same as a mixed colony?

A

No. Mixed colony can have cocci and bacilli together and gram variable has the same morphology

33
Q

Why does gram variable occur?

A 
Excessive decolorization
Overly thick smear
Excessive heat fixation
Old cultures
Poor quality stain (Iodine or Mordant being exposed to light)
34
Q

what test is used to confirm gram status when a gram variable occurs?

A

Potassium Hydroxide Test (KOH test)

35
Q

How do you perform a KOH test?

A
  1. A loopful of 3% KOH solution placed onto a slide
  2. Generous quantity of surface growth from culture & transferred to slide
  3. Stir with a loop
36
Q

What will develop a mucoid appearance and produce a sticky strand when lifted?

A

Gram negative bacteria

37
Q

What stain is used to ID acid-fast organisms?

A

Ziehl-Neelsen

38
Q

What acid-fast organisms does the Ziehl-Neelsen identify?

A

Mycobacterium and Nocardia

39
Q

What are the three parts of the Ziehl-Neelsen?

A

Primary Stain (RED)
Acid-Alcohol decolorizer
Counterstain (BLUE)

40
Q

What is the Giemsa stain used to detect?

A

Spirochetes and rickettsiae
Capsule of Bacillus anthracis
Morphology of Dermatophilus congolensis

41
Q

Can you use Diff-Quik to stain the slide if you do not have any of the other stains?

A

Yes but all of the bacteria will be purple

42
Q

What are the common quality controls you can purchase?

A

Staphylococcus aureus
Streptococcus spp
Escherichia coli

43
Q

Why do we stain?

A

Because morphology helps with ID

44
Q

What morphology characteristics help with ID?

A

Size
Shape
Arrangement
Presence of spores

45
Q

Bacilli

A

Shaped like rods/cylinders

46
Q

Cocci

A

Spherical cells

47
Q

Spirochetes

A

Occur singly and can be loose spirals, tight spirals and comma-shaped spirals

48
Q

Pleomorphic

A

Shapes ranging from cocci to rods

49
Q

Single Arrangement

A

Spirilla and most Bacilli

50
Q

Arrangement in pairs

A

Streptococcus pneumoniae (diplococcus)

51
Q

Chain Arrangement

A

Short/Long Streptococcus spp

52
Q

Tetrads Arrangement

A

“Quads”

53
Q

Cluster Arrangement

A

Staphylococcus aureus (grapelike)

54
Q

Palisades

A

“Chinese letter” pattern

Corynebacterium spp

55
Q

What do some genera bacteria produce?

A

Endospores

56
Q

Endospores

A

Resistant to heat, desiccation, chemicals and radiation

Lab techniques 2 (38 decks)

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