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243: microbiology > Ch. 38: Equipment & Supplies > Flashcards

Ch. 38: Equipment & Supplies Flashcards

1
Q

Why is laboratory safety so important when in a microbiology laboratory?

A

Most of the microorganisms encountered are potentially pathogenic, and many are zoonotic

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2
Q

Laboratory coats should be washed how often in hot water and strog bleach?

A

At least weekly

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3
Q

How are spilled cultures cleaned up?

A

Treated with disinfectant and allowed contact for 20 minutes before they are cleaned up

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4
Q

Nondisposable wire loops that have been contaminated with microbes must be _______ immediately after use

A

Flamed

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5
Q

What is the primary piece of equipment needed in a microbiology laboratory?

A

A good-quality incubator

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6
Q

Needed supplies for collecting and preparing bacterial and fungal samples

A
  • Sterile cotton-tipped applicators
  • Dull scalpel blades, scissors, and forceps
  • 3-20 mL syringes and 21-25 gauge needles
  • Sterile ET tube or jugular or urinary catheter
  • Collection tubes and preservatives
  • Rayon swab in a transport media (Culturette)
  • Glass slides and coverslips
  • Inoculating loops or wires and 10 mL calibrated loops
  • Bunsen burner or alcohol lamp
  • Candle jar or anaerobe jar
  • A variety of culture media (Plated and broth)
  • Antibiotic disks and dispensers
  • Gram stain
  • “Discard jar”
  • Wooden tongue depressors for handling feces
  • Racks to hold tubes and bottles
  • Refrigertor “cold packs” and polystyrene shipping containers for samples
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7
Q

What is a culture medium/media?

A

Any material solid or liquid that can support the growth of microorganisms

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8
Q

What forms of media are available for bacteriology?

A

Dehydrated powder, prepared agar plates, or ready to use liquid media for biochemical tests

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9
Q

What are the two types of solidifying agents used in the preparation of solid media?

A

Agar and gelatin

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10
Q

Agar definition

A

A gelatinous substance obtained from various kinds of red seaweed (agarophytes**) and used in biological culture media and as a thickener in foods

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11
Q

Gelatin defintion

A

A virtually colorless and tasteless water-soluble protein prepared from collagen (animal tissues)

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12
Q

Agar plates should be kept refrigerated at what degree celcius?

A

5-10

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13
Q

Why must plates be kept away from the internal walls of the refrigerator?

A

Contact with the jacket can freeze and ruin the media

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14
Q

How many general types of culture media are there?

A

6

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15
Q

What are the six types of general media used?

A
  1. Transport media
  2. General purpose media
  3. Enriched media
  4. Selective media
  5. Deifferential media
  6. Enrichment media
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16
Q

What types of media are those that contain multiple types of media in a single culture plate?

A

Modular media; these are common

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17
Q

General purpose media is also known as what?

A

Nutrient media; media is not commonly used

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18
Q

What is enriched media used for?

A

Formulated to meet the requirements of the most fastidious pathogen

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19
Q

What does enriched media contain?

A

They are basic nutrient media with extra nutrients added, such as blood, serum, or egg. This includes blood or chocolate agar

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20
Q

What is selective media made of?

A

Contain antibacterial substances, such as bile salts or antimicrobials, that inhibit or kill all but a few types of bacteria

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21
Q

What is an example of selective media?

A

MacConkey agar

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22
Q

What is differential media used for?

A

Used to allow bacteria to be differentiated into groups based on their biochemical reactions on the medium

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23
Q

What is an example of a differential media?

A

Simmons citrate

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24
Q

What is enrichment media used for?

A

Liquid media that favor the growth of a particular group of organisms. They contain nutrients that encourage the growth of the desired organisms or that contain inhibitory substances that suppress competitors

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25
Q

What are examples of enrichment media?

A

Tetrathionate broth and Selenite broth

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26
Q

What is transport media used for?

A

Designed to keep microbes alive while not encouraging growth and reproduction

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27
Q

A Culturette used for specimen collection is what type of media?

A

Transport media

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28
Q

What type of media is blood agar?

A

Acts as an enriched and differential media

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29
Q

What is the most commonly used blood agar?

A

Trypticase soy agar with sheep blood

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30
Q

How can blood agar act as an enriched and differential media?

A

Because four distinct types of hemolysis can be detected on blood agar

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31
Q

What are the four types of hemolysis that can occur on blood agar?

A

Alpha, Beta, Gamma, and Delta hemolysis

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32
Q

What is Alpha-hemolysis?

A

Partial hemolysis that creates a narrow band of greenish or slimy discoloration around the bacterial colony

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33
Q

What is Beta-hemolysis?

A

Complete hemolysis that creates a clear zone around the bacterial colony

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34
Q

What is Gamma-hemolysis?

A

Hemolysis that produces no change in the appearance of the medium and no hemolysis around colonies

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35
Q

What is another word for hemolysis?

A

Hematolysis

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36
Q

What is Delta-hemolysis?

A

A zone of hemolysis surrounded by a narrow zone of hemolysis around a bacterial colony

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37
Q

What is another name for Delta-hemolysis?

A

Double-zone hemolysis

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38
Q

Bacteria can be classified on the basis of their patterns of _______ in blood agar

A

Hemolysis

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39
Q

What type of media are MacConkey and Eosin-Methylene Blue agar?

A

Selective and differential media

40
Q

What does MacConkey agar contain?

A

Crystal violet (which suppresses the growth of gram-positive bacteria), bile salts that are selective for lactose-fermenting Enterobacteriaceae, and a few other bile salt tolerant gram-negative bacteria

41
Q

With or without growth, MacConkey agar may be used as a test for the primary indication of what bacteria?

A

Gram-negative genera

42
Q

EMB media performs the same function as MacConkey agar and may also be used to identify lactose-fermenting organisms.

True or False?

A

True

43
Q

What are the indicators in MacConkey agar?

A

Lactose and neutral red

44
Q

Examples of lactose-fermenting organisms

A

Escherichia coli, Enterobacter, and Klebsiella species

45
Q

Lactose-fermenting organisms produce acid from lactose and grow as _________ colonies on the MacConkey medium.

A

Pinkish-red

46
Q

What is lactose?

A

A sugar present in milk. It is a disaccharide containing glucose and galactose units

47
Q

What happens to the medium when bacteria can’t ferment lactose?

A

The bacteria will attack the peptone in the MacConkey agar and produce an alkaline reaction and colorless colonies

48
Q

When both a MacConkey and blood agar plates are used with one specimen, what information can it provide?

A

For example, no growth on the MacConkey agar plate but good growth on the blood agar suggests that the isolated pathogen is probably a gram-positive organism. This can be valuable information

49
Q

What type of media are chromogenic agars?

A

Selective and differntial

50
Q

Chromogenic definition

A

Producing a pigment from bacteria

51
Q

What is the biggest advantage of chromogenic agar?

A

This allows for more rapid identification of bacteria and saves time and costs because additional biochemical tests may not be needed

52
Q

Types of chromogenic agar are designed to identify certain resistant bacteria based on what?

A

Color and colony appearance

53
Q

An additional type of chromogenic agar is used to differentiate E. coli from other enteric bacteria.

On an E. coli agar, E. coli will be ________ in color whereas other enteric bacterial will be ______ in color.

A

Dark blue-green; magenta

54
Q

What is the full name of E. coli?

A

Escherichia coli

55
Q

When using a chromogenic agar, if non-enteric bacteria are inhibited on the media, what color will they be?

A

Colorless because it only shows enteric bacteria as colored

56
Q

Thioglycollate broth is used specifically on what kind of bacteria?

A

Anaerobic

57
Q

What is Thioglycollate broth used for?

A

A liquid medium that is used to culture anaerobic bacteria to determine the oxygen tolerance of microbes

58
Q

What is the primary use of Thioglycollate broth in vet med?

A

Used as an enrichment media and for blood cultures

59
Q

What is the structure of Thioglycollate broth?

A

The medium contains a stable oxygen gradient, with high concentrations of oxygen near the surface and anaerobic conditions near the bottom. Obligate aerobes will grow in the oxygen-rich top layer, whereas obligate anaerobes will grow in the lower part of the tube

60
Q

Can facultative anaerobes grow in a Thiglycollate broth?

A

Yes, they may grow throughout the medium but will primarily grow in the middle of the tube

61
Q

How should urea slants be incubated?

A

They are streaked with inoculum and incubated overnight at 37 degrees celsius (This is a liquid medium)

62
Q

What color is urea medium?

A

Peach

63
Q

Hydrolyze definiton

A

The break down by chemical reaction with water

64
Q

In what case will urea medium change to a pink color?

A

If the bacteria hydrolyze the urea in the medium, ammonia production turns the medium to a pink color

65
Q

Sulfide-Indole Motility is a liquid medium.

True or False?

A

True

66
Q

What is the technique for inoculation when using Sulfide-Indole Motility (SIM)?

A

The medium is inoculated with a straight stab of the loop to a depth of approximately 1 inch and carefully removed

67
Q

In a SIM medium, hydrogen sulfide production is indicated by what color?

A

Blackening of the medium

68
Q

How can Indole production be assessed with a SIM medium?

A

5 drops of Kovac’s reagent need to be added to the top of the medium

69
Q

How will the medium react if tryptophan has been broken down to indole by the bacteria in the tube of a SIM medium?

A

A red ring will immediately form on top of the medium

70
Q

How are Simmons citrate media tubes used?

A

They differentiate bacteria according to their use of citrate

71
Q

What is inoculated in a simmons citrate tube?

A

The slanted surface

72
Q

What colors may you see during positive and negative reactions when using a simmons citrate media?

A

Positive: Deep blue
Negative: Green

73
Q

What is triple sugar iron agar used for?

A

For the presumptive identification of salmonellae and the initial differentiation of enteric bacteria

74
Q

What type of medium is brain-heart broth?

A

General purpose

75
Q

What is brain-heart broth used for?

A

Used to increase the number of organisms (pre enrichment) before they are plated on a solid medium

76
Q

Why does blood need to be diluted in broth when doing a blood culture?

A

Blood contains many substances that are inhibitory to bacteria, adding the blood sample directly to broth dilutes the effect of these natural inhibitors

77
Q

What agar is not routinely used, but is a highly selective medium for staphylococci?

A

Mannitol Salt Agar

78
Q

Staphylococci are ______ tolerant.

A

Salt

79
Q

What are the two factors included in mannitol salt agar?

A

High salt content and a pH indicator phenol red

80
Q

What is phenol red?

A

A red dye used as a pH indicator

81
Q

S. aureus (but usually not staphylococcus epidermidis) _______ mannitol.

A

Ferments

82
Q

Mannitol Salt Agar is a liquid medium.

True or False?

A

False

83
Q

When using mannitol salt agar, if the bacteria is able to survive the salt content and ferment mannitol resulting in a positive reaction, what color will the agar change to?

A

Yellow; from red

84
Q

What kind of media is Mueller-Hinton Agar?

A

General-purpose

85
Q

What is Mueller-Hinton agar primarily used for?

A

For the performance of the agar diffusion antimicrobial sensitivity test

86
Q

Sabouraud Dextrose and “biggy” medias are used specifically for the culture of what?

A

Fungi and yeasts

87
Q

“Biggy” is a common reference to what?

A

Bismuth-Glucose-Glycine-Yeast Media

88
Q

Dermatophyte test media in vet med is composed of what?

A

Sabouraud dextrose agar

89
Q

What is a dermatophyte test medium?

A

A differential culture medium designed to support the growth of cutaneous fungal organisms and to inhibit bacterial growth

90
Q

Dermatophyte definiton

A

A pathogenic fungus that grows on skin, mucous membranes, hair, nails, feathers, and other body surfaces, causing ringworm and related diseases

Fungus that requires keratin for growth and cause skin diseases

91
Q

What are examples of multi-chambered agar plates that contain both selective and non-selective media?

A

Bullseye and Spectrum CS

92
Q

A bullseye culture plate contains an agar as a circle in the middle of the plate. What agar is this?

A

Mueller-Hinton agar; used for sensitivity testing

93
Q

Uri-Cult can be referred to as what?

A

“Dipslides” or “paddle” media

94
Q

What is Uri-Cult used for?

A

UTI screening

95
Q

Uricult most commonly includes what agars?

A

Either MacConkey or EMB and cystine lactose electrolyte-deficient (CLED) agar

96
Q

How is a Uricult assessed after it has incubated?

A

A colony count is performed, and the color of the CLED agar is compared with a chart for presumptive identification

97
Q

What is the purpose of a bunsen burner?

A

To warm up the non-disposable inoculating loops

243: microbiology (11 decks)

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