PREPARATION OF BACTERIAL CULTURE MEDIA Flashcards

1
Q

is the process of growing microorganisms in culture by taking bacteria from the infection site by some means of specimen collection and growing them in the artificial environment of the laboratory.

A

Cultivation

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2
Q

are incorporated into culture media on or in which bacteria are grown.

A

Nutrients

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3
Q

Nutrients usually include…

A

proteins/peptides/amino-acids, carbohydrates, essential metals and minerals like calcium, magnesium, iron, phosphates, sulphates etc.

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4
Q

such as phosphates and acetates are also incorporated.

A

Buffering agents

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5
Q

Various types of culture media have been developed for use in diagnostic microbiology because different pathogenic bacteria have different nutritional needs.

For certain bacteria that require complex and exceptional media components such as growth factors and vitamins, these bacteria are said to be..

A

fastidious.

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6
Q

the nutritional needs of most clinically important bacteria are relatively basic and straightforward and are considered…

A

non-fastidious.

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7
Q

In diagnostic bacteriology there are four general categories of media:

A

enrichrent (or enriched)
supportive (general)
selective
differential

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8
Q

_ These contain specific nutrients required for the growth of bacterial pathogens that may be present alone or with other bacterial species in a patient specimen.

A

Enriched media

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9
Q

This media type is used to enhance the growth of a particular bacterial pathogen from a mixture of organisms by using nutrient specificity.

A

Enriched media

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10
Q

One example of such a medium is buffered charcoal yeast extract agar, which provides L-cysteine and other nutrients required for the growth of Legionella pneumophila, the causative agent of legionnaire’s disease.

A

Enriched media

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11
Q

is similar to enriched media, however, this is in liquid form.

A

• Enrichment media

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12
Q

Twe enrichment broths generally used for stool specimens are_______ for alkaline-loving bacteria like the Vibrio species and _______ to enhance Salmonella and Shigella growth.

A

• Enrichment media

alkaline peptone water (APW)

Selenite-F

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13
Q

These contain nutrients that support growth of most non-fastidious organisms without giving any organism a growth advantage, for example, Nutrient Agar.

A

Supportive media

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14
Q

• These contain one or more agents that are inhibitory to all organisms except those being sought.

A

Selective media

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15
Q

These media select for the growth of certain bacteria to the disadvantage of others.

Inhibitory agents used for this purpose include…

A

Selective media

dyes, bile salts, alcohols, acids, and antibiotics

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16
Q

An example of a selective medium is________, which inhibits the growth of aerobic and facultatively anaerobic grarn-negative rods and allows gram-positive cocci to grow.

A

phenylethyl alcohol agar

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17
Q

• These employ some factor (or factors) that allows colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics that can be used to distinguish them from other bacteria growing on the same agar plate.

A

Differential media

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18
Q

One commonly used differential medium is the______, which differentiates between grarn-negative bacteria that can and cannot ferment the_____.

A

MacConkey agar

sugar lactose

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19
Q

Of importance, many media used in diagnostic bacteriology provide more than one function.

For example, _______is both differential and selective because it will not allow most gram-positive bacteria to grow.

A

MacConkey agar

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20
Q

Another example is_______.

This is the most used supportive medium for diagnostic bacteriology because it allows many organisms to grow.

However, in many ways this agar is also differential because the appearance of colonies produced by certain bacterial species is readily distinguishable.

A

sheep blood agar.

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21
Q

Storage: Stack agar plates upside down in the refrigerator. Do Not Freeze!

Why?

A

The purpose of placing the plates upside down is to prevent condensation from dripping down onto the agar surface which could then facilitate swarming of organisms or cause contamination.

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22
Q

CULTURE MEDIA

• provides the________ for microbial growth

A

appropriate biochemical and biophvsical environment

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23
Q

Culture media: 2 Types

A
  • Inoculum
  • Culture
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24
Q

3 types of culture

A

Pure
Mixed
Stock

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25
Q

Types of COLONY

A

Mucoid colony
Smooth colony
Rough colony

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26
Q

” any material containing the necessary nutritional and environmental
requirements for bacterial growth

A

CULTURE MEDIA

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27
Q

• CLASSIFICATION of CULTURE MEDIA according to:

A

PHYSICAL STATE/ CONSISTENCY
COMPOSITION
HOW THE MEDIUM IS DISPENSED
USE

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28
Q

ACCORDINGTO PHYSICAL STATE/ CONSISTENCY:

A

Liquid
Semisolid
Solid

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29
Q
  • without any trace of agar or solidifying substances (e.g. nutrient broth)
A

LIQUID

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30
Q
  • contains 0.5-1.5% of agar (e.g. Sulfide Indole Motility)
A

SEMISOLID

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31
Q

SEMISOLID- contains

A

0.5-1.5% of agar (e.g. Sulfide Indole Motility)

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32
Q
  • contains 2-3% of agar (e.g. Blood Agar Plate, Triple Sugar Iron)
A

SOLID

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33
Q

SOLID- contains

A

2-3% of agar (e.g. Blood Agar Plate, Triple Sugar Iron)

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34
Q

Pure culture

A

Only 1 microorganism present

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35
Q

Mixed culture

A

More than 1 microorganism present

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36
Q

Stock culture

A

Keep the viability of the microorganism

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37
Q

Types of bacteria based on growth conditions

focc mt

A

Facultative anaerobe
Obligate microbes
Cryophiles
Capnophilic organisms
Microaerophilic microorganisms
Thermophiles

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38
Q

2 obligate microbes

A

Obligate aerobes
Obligate anaerobes

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39
Q

Obligate aerobes

A

Strictly require O2 to live

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40
Q

Obligate anaerobes

A

Strictly require no O2 to live

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41
Q

Microaerophlic microorganisms

A

Requires 5-10% O2 to grow (optimal growth)

42
Q

Facultative anaerobes

A

Able to grow with or without O2

43
Q

Capnophilic organisms

A

Require CO2 to grow
Incubated in the gas pak jar/ can

44
Q

Thermophiles

A

Require high temperature

45
Q

Psychrophiles or cryophiles

A

Require extremely low temperature to grow

46
Q

Signs of bacterial growth in liquid culture

A

Turbidity

47
Q

CULTURE MEDIA
ACCORDINGTO COMPOSITION:

A

SYNTHETIC OR DEFINED MEDIUM

NON SYNTHETIC OR COMPLEX MEDIUM

TISSUE CULTURE MEDIUM

48
Q

Medium which all components are known (commercially prepared culture media)

A

SYNTHETIC OR DEFINED MEDIUM

49
Q

Preferred for the isolation of cyanobacteria and chemoorganotrophs.

A

SYNTHETIC OR DEFINED MEDIUM

50
Q

Example: BG II MEDIUM

A

SYNTHETIC OR DEFINED MEDIUM

51
Q

Example: TSB. MAC

A

NON SYNTHETIC OR COMPLEX MEDIUM

52
Q

Isolation of MEDICALL IMPORTANT BACTERIA

A

NON SYNTHETIC OR COMPLEX MEDIUM

53
Q

Medium which some of the substances are unknown (peptones, meat and yeast

A

NON SYNTHETIC OR COMPLEX MEDIUM

54
Q

Example: WI38 CELLS, HeLa 229 CELLS, MCCOY CELLS

A

TISSUE CULTURE MEDIUM

55
Q

Obligate intracellular bacteria (Rickettsia and Chlamydia)

A

TISSUE CULTURE MEDIUM

56
Q

Uses live tissues for organisms to survive

A

TISSUE CULTURE MEDIUM

57
Q

CULTURE MEDIA
ACCORDINGTO DISPENSING OR DISTRIBUTION:

A

Plated
Tubed

58
Q

• Distributed in sterile petri dish or plates

A

PLATED

59
Q

TUBED
Tube media are prepared as either

A

LIQUID
SLANT
BUTT AND SLANT
BUTT

60
Q

CULTURE MEDIA
ACCORDINGTO DISPENSING OR DISTRIBUTION:

” TRIPLE SUGAR IRON

A

Slant and butt

61
Q

ACCORDINGTO DISPENSING OR DISTRIBUTION:

” LYSINE IRON AGAR

A

Slant and butt

62
Q

CULTURE MEDIA
ACCORDINGTO DISPENSING OR DISTRIBUTION:

” SIMMONS’ CITRATE

A

Slant

63
Q

CULTURE MEDIA
ACCORDING TO DISPENSING OR DISTRIBUTION:

CHRISTENSENS UREA AGAR

A

Slant

64
Q

CULTURE MEDIA
ACCORDINGTO DISPENSING OR DISTRIBUTION:

” SULFIDE INDOLE MOTILITY

A

Deed Semi-solid

65
Q

nutrient agar

A

General purpose

66
Q

• supports most non-fastidious bacteria
• for primary isolation of microorganism

A

GENERAL PURPOSE MEDIA

• BASAL MEDIA

67
Q

• Designed to grow a broad spectrum of microbes

A

General purpose media

68
Q

Examples of general purpose media

A

Examples:
• Nutrient agar
• Nutrient broth

69
Q

• Supports growth of fastidious organisms

A

ENRICHED

70
Q

• Addition: blood, serum, egg yolk, vitamins, AA

A

ENRICHED

71
Q

Examples of ENRICHED

A

+ BAP
# CAP
# Thayer - Martin

72
Q

Functional Type:

• Promotes growth of certain organisms

A

ENRICHMENT

73
Q

Examples of ENRICHMENT

A

• Examples:
•Selenite F
• BHI
•Thioglycollate

74
Q

Functional Type:

• contains inhibitory agents that prevents / suppress growth of unwanted microbes
• permits preliminary identification of genus or spp.

A

SELECTIVE

75
Q

Examples of SELECTIVE

A

Examples:
• Mannitol Salt Agar
• Hektoen Enteric Agar

76
Q

Functional Type:

• displays visible differences among microbes

A

DIFFERENTIAL

77
Q

Examples of DIFFERENTIAL

A

MacConkey agar
Spirit blue agar

78
Q

MacConkey agar
= indicates lactose fermentation

A

Neutral red

79
Q

Spirit blue agar
= indicates fat hydrolysis

A

Spirit blue dye

80
Q

• Make it easy to distinguish colonies of different microbes.

A

Differential Media

81
Q

Refers to partial hemolysis, producing a greenish discoloration around colonies due to the oxidation of hemoglobin to methemoglobin.

A

Alpha Hemolysis (α)

82
Q

Indicates complete hemolysis, creating a clear zone around colonies as red blood cells are fully lysed.

A

Beta Hemolysis (β)

83
Q

Signifies no hemolysis, where there is no change in the medium around colonies, indicating no destruction of red blood cells.

A

Gamma Hemolysis (γ)

84
Q

Growth media are primarily used in two phases: either

A

broth (liquid) or agar (solid)

85
Q

In broth media, nutrients are dissolved in water, and bacterial growth is indicated by…

A

a change in the broth’s appearance from clear to turbid (cloudy).

86
Q

The____, of the broth results from light deflected by bacteria present in the culture

A

turbidity, or cloudiness

87
Q

Some broths may also contain a pH indicator, such as____, that may change color in the presence of bacterial metabolites rather than relying solely on the growth of the organism.

A

phenol red

88
Q

Strict anaerobes will grow at the____ of the broth tube, whereas aerobes will grow____

A

bottom

near the surface.

89
Q

_____, the most common solidifying agent, has the unique property of melting at high temperatures (295°C) and solidifying after the temperature fa. below 50°C.

A

Agar

90
Q

The petri dish containing the agar is an..

A

agar plate

91
Q

Solid media may also be placed in tubes; a tube with a flat surface is an____ and a tube with a slanted surface is an____.

A

agar deep

agar slant

92
Q

the resulting bacterial population is considered to be derived from a single bacterial cell and is known as a…

A

pure colony

93
Q

This media type is used to enhance the growth of a particular bacterial pathogen from a mixture of organisms by providing specific nutrients for the organism’s growth.

A

Enrichment media

94
Q

contain specific nutrients required for the growth of particular bacterial pathogens that may be present alone or with other bacterial species in a patient specimen.

A

Enrichment media

95
Q

also includes specialized enrichment broths used to enhance the growth of organisms present in low numbers.

A

Enrichment media

96
Q

Broths used to ensure growth of organisms that do not grow on solid media, and that do not contain specific nutrients to enhance the growth of microor-ganisms, are referred to as…

A

back-up broths

97
Q

contain nutrients that support growth of most nonfastidious organisms without giving any particular organism a growth advantage.

A

Nutritive media

98
Q

include tryptic soy agar and nutrient agar plates for bacteria, or Sabouraud’s dextrose agar for fungi.

A

Nutrient media

99
Q

contain one or more agents that are inhibitory to all organisms except those “selected” by the specific growth condition or chemical.

A

Selective media

100
Q

In other words, these media select for the growth of certain bacteria to the disadvantage of others.

A

Selective media

101
Q

Inhibitory agents used for this purpose include dyes, bile salts, alcohols, acids, and antibiotics.

A

Selective media

102
Q

employ some factor (or factors) that allows colonies of one bacterial species or type to exhibit certain metabolic or culture characteristics that can be used to distinguish them from other bacteria growing on the same agar plate.

A

Differential media