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Bacte LAB > DIFFERENTIAL STAINING METHODS > Flashcards

DIFFERENTIAL STAINING METHODS Flashcards

1
Q

Stains

A

Gram stain

Acid fast stain (Ziehl-Neelsen Method)

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2
Q

Gram stain:

A

• Crystal violet
• Gram’s iodine
• Acetone alcohol or 95% Ethyl alcohol
• Safranin

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3
Q

Acid fast stain (Ziehl-Neelsen Method):

A

Carbol fuchsin
Acid alcohol
Methylene blue

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4
Q

refers to the form or shape of the cell as seen through the microscope.

A

Bacterial morphology

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5
Q

Bacteria come in various sizes and shapes.

Most bacteria range from_____ in diameter and from_____ in length.

A

0.2-2.0 um

2-8 um

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6
Q

Bacteria

There are three (3) forms generally recognized on the basis of the shape of the bacteria.

A

Cocci
Rods
Spiral

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7
Q

These are usually round in shape but can be oval, elongated, or flattened on one side.

A

Cocci

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8
Q

“Cocci” means, “_____” in Greek.

A

berry

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9
Q

When_____ divide to reproduce, the cells can remain attached to one another.

A

cocci

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10
Q

Cocci

Genus

A

Staphylococcus
Diplococcus
Streptococcus
Sarcina

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11
Q

Staphylococcus

A

irregular or grapelike-like clusters

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12
Q

Diplococcus

A

in pairs

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13
Q

Streptococcus

A

in chains

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14
Q

Sarcina

A

in cuboidal pockets of eight

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15
Q

Rod shape bacteria divide only across their short axis, so there are fewer groupings than of cocci.

A

Rods

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16
Q

Most____ appear in single with straight, sausage, and cylindrical or elongated shapes.

Others have tapered ends, like____.

A

rods

cigars

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17
Q

Rods

Still others are oval and look so much like cocci, called,_______.

A

coccobacilli

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18
Q

Rods shaped bacteria are called “____” which means, “little sticks”.

A

Bacilli

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19
Q

Bacillus

A

In chains

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20
Q

Clostridium

A

Singly

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21
Q

Corynebacterium

A

palisade or Chinese letter

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22
Q

Rods

Genus

A

Bacillus
Clostridium
Corynebacterium

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23
Q

Curved rods resembling a comma shape are called______.

An example is_______, the causative agent of cholera.

A

Vibrios

Vibrio cholerae

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24
Q

bacteria have one or more twists; they are never straight but resembles helicoidal or corkscrew shape.

A

Spiral

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25
Q

The spiral bacteria are divided as follows.

A

Spirilla
Spirochetes

26
Q

actual or complete spirals, helices or may resemble the appearance of a cork-screw.

A

Spirilla

27
Q

Its body is relatively rigid.

Example is______, the agent of rat bite fever.

A

Spirilla

Spirillum minor

28
Q

” look like spirilla but their bodies are flexible and they wiggle while moving.

Example is ______, the causative agent of syphilis

A

Spirochetes

Treponema pallidu

29
Q

” a bacterial suspension is dried and heat fixed so that it will adhere to the
slide.

Such smear can then be stained with colored dyes.

A

Fixed-stained smear

30
Q

Vibrio cholerae

A

Curved rod

31
Q

Spirillum minor, the agent of rat bite fever.

A

Spirilla

32
Q

Example is Treponema pallidum, the causative agent of syphilis

A

Spirochete

33
Q

This staining method uses more than one type of stain to create a contrast between two or more organisms of the same or different species that are being studied.

A

DIFFERENTIAL STAINING

34
Q

used to compare the response of the organism with different physiological characteristics to certain staining techniques.

A

DIFFERENTIAL STAINING

35
Q

Differential staining is also called_____ because it involves the use of at least two dyes.

A

multiple staining

36
Q

Reagents Used in Differential Staining

A
  1. Initial stain
  2. Mordant
  3. Decolorizer
  4. Secondary stain
37
Q
  • also known as the primary stain
A

Initial stain

38
Q

it is the first stain that is applied on the specimen.

A

Initial stain

39
Q
  • any substance which will form a bridge between the cell and the initial stain, so that the cell being studied will better retain the stain.
A

Mordant

40
Q

Types of mordant:

A

Physical mordant
Chemical mordant

41
Q

a. - such as heat or cold
b. - such as lodine, Ferrous sulphate,
Tannic acid

A

Physical mordant

Chemical mordant

42
Q
  • substance used to remove the initial stain.
A

Decolorizer

43
Q

This will help in differentiating the physiological characteristic or some special structure that are present in the cell

A

Secondary stain

44
Q

also known as the counterstain.

A

Secondary stain

45
Q

It is the stain that is applied to the decolorized cell or cell parts.

A

Secondary stain

46
Q

was developed in 1884 by the Danish bacteriologist Hans Christian Gram.

It is one of the most useful staining procedures because it classifies bacteria into two large groups: gram positive and gram-negative bacteria.

A

Gram stain

47
Q

Gram stain was developed in 1884 by the Danish bacteriologist

A

Hans Christian Gram

48
Q

Steps in Gram staining:

  1. A heat-fixed smear is covered with a basic purple dye, usually_____.
  2. After a short time, the purple dye is washed off and the smear is covered with______. When the iodine is washed off, both gram (+) and gram (-) bacteria appear______.
  3. The slide is washed with alcohol or an alcohol acetone solution. This solution is a______, which removes the purple from the cells of some species but not from others.
  4. The alcohol is rinsed off, and the slide is then stained with_____, a basic red dye. The smear is washed again, blotted dry, and examined microscopically.
A

crystal violet

iodine (mordant)

dark violet or purple

decolorizing agent

safranin

49
Q

Bacteria that retain the dark violet or purple color are classified as______ while bacteria that lose the dark violet or purple color after decolorization are classified as______.

A

gram positive

gram-negative.

50
Q

Different kinds of bacteria react differently to the Gram stain, because:
1. Structural differences in their cell walls affect the retention or escape of a combination of crystal violet and iodine, called the _____
2. ______ bacteria have a thicker peptidoglycan cell wall than ______
bacteria.
3. Gram (-) bacteria contain a layer of ______ as part of their cell wall.

A

crystal violet-lodine
complex

Gram (+)

gram (-)

lipopolysaccharide

51
Q

Gram stain

When applied to both gram (+) and gram (-) cells, crystal violet and then iodine readily enter the cells.

Inside the cells, the crystal violet and iodine combine to form______.

This complex is larger than the crystal violet molecule that entered the cells, and, because of its size it cannot be washed out of the intact peptidoglycan layer of_____ cells by alcohol.

A

CV-I complex

gram (+)

52
Q

Gram stain

• Consequently, grams (+) cells retain the color of the crystal violet dye. In gram (-) cells, however, the alcohol disrupts the_______, and the CV-I complex is washed out through the thin layer of peptidoglycan.

” As a result, gram (-) cells are colorless until counterstained with_____,
after which they are pink.

A

outer lipopolysaccharide layer

safranin

53
Q

_____cells retain the dye and remain purple.

______cells do not retain the dye; they are colorless until counterstained with a red dye, after which they appear pink.

A

Gram (+)

Gram (-)

54
Q

Errors in Gram Staining
Gram (+) becomes; Gram (-)

A

• Acidic Gram’s iodine, Insufficient iodine
•Aging, dying, autolysis, overheating.
•Removal of MgRNA with precipitation fror bile salts in the culture media
•Low concentration of crystal violet
•Over decolorization
•Excessive washing, excessive counterstaining

55
Q

Errors in gram staining

Gram (+) becomes Gram (+)

A

• Inadequate decolorization
• Thick smears

56
Q

The cell wall of some organisms, such as those belonging to the Genus Mycobacterium, contains a substantial amount of_____.

A

lipids

57
Q

are very difficult to stain because it resists penetration of the primary dye into the cellular cytoplasm.

A

Lipids

58
Q

Lipids are hard to penetrate

Because of this factor, application of heat or prolonging the exposure of the smear with the primary dye is needed.

Once stained, these organisms retain the stain so that even acid alcohol could not remove it. Hence, they are referred to as_____.

A

acid fast

59
Q

Steps in Acid-Fast staining:
A.______ is applied to a fixed smear, and the slide is gently____ for several minutes.

B. Slide is cooled and washed with water.

C. Smear is next treated with_____, which removes the red stain from bacteria that are not acid-fast.

D. The smear is then stained with a_____ counterstain. Nonacid-fast cells appear_____ after application of the counterstain.

A

Red dye carbolfuchsin; heated

acid alcohol, a decolorizer

methylene blue

blue

60
Q

The______ microorganisms retain the red color because the carbolfuchsin is more soluble in the cell wall lipids than in the acid-alcohol.

A

acid-fast

61
Q

• In ______bacteria, whose cell wall lacks the lipid components, the carbolfuchsin is rapidly removed during decolorization, leaving the cells colorless.

A

non-acid fast

Bacte LAB (15 decks)

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