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Clinical Bacteriology > (P) Lec 4: Culture Staining (Part 2) > Flashcards

(P) Lec 4: Culture Staining (Part 2) Flashcards

1
Q

Cultivation Methods

Fill in the blanks:
Consider the following factors:
1. Choice of suitable (blank)
2. Isolation of bacterial organism in (blank) culture

A
  1. Medium
  2. Pure
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1
Q

Cultivation Methods

The process of growing microorganisms in culture by taking bacteria from an infection site

A

Bacterial Culture (the gold standard)

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2
Q

Cultivation Methods (main purposes)

Fill in the blanks:
To grow and isolate all bacteria present in a (blank) specimen

A

Clinical

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3
Q

Cultivation Methods (main purposes)

Fill in the blanks:
To determine which of the bacteria are most likely causing a/an (blank) and which are contaminants/colonizers

A

Infection

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4
Q

Cultivation Methods (main purposes)

Fill in the blanks:
To obtain sufficient growth of clinically (blank) bacteria to allow identification, characterization, and susceptibility testing

A

Relevant

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5
Q

Cultivation Methods

This depends on the availability of essential nutrients & appropriate environmental conditions

A

Bacterial Survival

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6
Q

Cultivation Methods

TOF: Bacteria will grow once plated

A

False (recall the optimum conditions for growth)

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7
Q

Phase of Growth Media

  • Are nutrients dissolved in water
  • Turbidity/cloudiness is a positive result for the presence of bacteria
A

Liquid or Broth

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8
Q

Phase of Growth Media

How much of the bacterial concentration is needed for turbidity to be detected in the liquid/broth media?

A

10^6 bacteria/mL

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9
Q

Phase of Growth Media

A combination of a solidifying agent added to the nutrients and water

A

Solid or Agar

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10
Q

Phase of Growth Media

What is the most common solid/agar media?

A

Agarose

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11
Q

Phase of Growth Media

What is the melting temperature and re-solidification temperature of agarose?

A

Melting: >95ºC
Re-solidification: <50ºC

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12
Q

Phase of Growth Media

This phase of the medium comprises of a semi-solid characterization, what is it called?

A

Biphasic/Intermediate Phase (for bacterial motility)

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13
Q

Media Classification and Functions

This comes with specific nutrients that will enhance pathogen growth

A

Enrichment Media

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14
Q

Media Classification and Functions

Identify the media:
Examples are BCYA (with lysine), Thioglycollate, LIM Broth, and GN Broth

A

Enrichment Media

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15
Q

Media Classification and Functions (Enrichment Media)

Buffer Charcoal Yeast Agar (BCYA) with lysine in the Enrichment Media supports the growth of what bacteria?

A

L. pneumophilia (lysine supports the growth of this)

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16
Q

Media Classification and Functions (Enrichment Media)

Thioglycollate supports the growth of what bacteria?

A

Anaerobes (because thioglycollate and cystine remove O2)

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17
Q

Media Classification and Functions

This contains agents that are inhibitory to all organisms except those selected for specific growth

A

Selective Media

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18
Q

Media Classification and Functions (Selective Media)

PEA supports/allows the growth of what bacteria?

A

Gram (+) bacteria

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19
Q

Media Classification and Functions (Selective Media)

Thayer-Martin supports/allows the growth of what bacteria?

A

Neisseria gonorrhea

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20
Q

Media Classification and Functions

This supports the growth of non-fastidious organisms (only the basic needs for growth)

A

Nutritive/Supportive Media

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21
Q

Media Classification and Functions (Nutritive/Supportive Media)

Tripticase Soy Agar (TSA), Nutrient Agar, and Sabouraud Dextrose Agar (SDA) supports the growth of what bacteria?

A

Most organisms

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22
Q

Media Classification and Functions (Nutritive/Supportive Media)

This bacteria requires basic needs only

A

Non-Fastidious Organisms

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23
Q

Media Classification and Functions (Nutritive/Supportive Media)

This bacteria requires specific/complex requirements for growth

A

Fastidious Organisms

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24
Q

Media Classification and Functions

This allows bacteria to exhibit certain metabolic or cultural characteristics that can be used to distinguish them from other bacteria (e.g. MAC and BAP)

A

Differential Media

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25
Q

Media Classification and Functions (Differential Media)

This is both a differential (demonstrates whether the organisms are lactose fermenters or not) and selective (for gram negative) media

A

MacConkey Agar (MAC)

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26
Q

Media Classification and Functions (Differential Media)

What is the positive indicator for the presence of lactose fermenters in MAC agar?

A

Pink colonies

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27
Q

Media Classification and Functions (Differential Media)

What is the negative indicator for the presence of lactose fermenters in MAC agar?

A

Colorless colonies

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28
Q

Media Classification and Functions (Differential Media)

This is a nutritive and differential media that supports the growth of most fastidious organisms and a differential media that demonstrates the hemolytic pattern of bacteria

A

Blood Agar Plate (BAP)

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29
Q

Media Classification and Functions (Differential Media)

Some microorganisms have this enzyme which hemolyzes blood and can be seen in the agar plate

A

Hemolysin

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30
Q

Plating Media

This nutritive media supports the growth for all and most fastidious bacteria and demonstrates a hemolytic pattern

A

Sheep Blood Agar

Has 5% defibrilgenated sheep’s blood

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31
Q

Plating Media (Sheep’s Blood Agar)

Refers to the complete clearing of RBCs around the bacterial colony

A

Beta hemolysis

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32
Q

Plating Media (Sheep’s Blood Agar)

Refers to greenish discoloration

A

Alpha hemolysis

33
Q

Plating Media (Sheep’s Blood Agar)

Refers to no hemolysis

A

Gamma hemolysis

34
Q

Plating Media

Uses hemolyzed blood and supports the growth of fastidious bacteria (same as BAP)

A

Chocolate Agar Plate

35
Q

Plating Media (Chocolate Agar Plate)

The hemolyzed blood releases 2 factors which support the growth of fastidious bacteria

A

Factor X (hemin) and Factor V (NAD)

e.g. Haemophilus spp. and Neisseria gonorrhea

36
Q

Plating Media

This has colistin and nalidixic acid (antibiotics) which inhibits gram-negative bacteria and selective for gram-positive bacteria

A

Columbia (SNA) with Blood Agar

37
Q

Plating Media

This is both a selective agar and differential agar with crystal violet as an inhibitor for gram (+) bacteria and fungi

A

MacConkey Agar

38
Q

Plating Media (MacConkey)

What is the indicator for MAC after crystal violet has inhibited the growth of gram-positive bacteria and fungi?

A

Neutral Red (pH indicator)

When there is a change in pH, there’ll be a change in the indicator too

39
Q

Plating Media (MacConkey)

When there is bacterial fermentation of lactose, there is a production of acid which manifests as what result?

A

Pink Colonies

Due to decreased pH

40
Q

Plating Media

This has bile salts and dyes as the inhibitors (bromothymol blue and acid fuchsin)

A

Hektoen Enteric Agar (HEA)

41
Q

Hektoen Enteric Agar (HEA) is the selective media for what 2 bacteria?

A

Salmonella and Shigella

+ other gram positive bacteria

42
Q

Plating Media (Hektoen Enteric Agar)

For the differential factor, non-enteric pathogens will not grow and will appear as what color?

A

Orange to salmon-colored

43
Q

Plating Media (Hektoen Enteric Agar)

This can differentiate between what 2 kinds of organisms involving lactose?

A

Lactose-producing and non lactose-producing

44
Q

Plating Media (Hektoen Enteric Agar)

TOF: This uses gram positive organisms

A

False (gram negative)

45
Q

Plating Media (Hektoen Enteric Agar)

This can differentiate between what 2 kinds of organisms involving hydrogen sulfide?

A

H2S producer and non-H2S producer

46
Q

Plating Media (Hektoen Enteric Agar)

What is the pH indicator?

A

Bromthymol blue

47
Q

Plating Media (Hektoen Enteric Agar)

Presence of lactose indicates many changes in colonies, what is manifested when there are no lactose-fermenters?

A

No color change

48
Q

Plating Media (Hektoen Enteric Agar)

What is the indicator for H2S (hydrogen sulfide) and what will be the color of the colonies?

A

Ammonium Citrate; Black

49
Q

Plating Media

This is selective and differential for Shigella spp. and Salmonella spp.

A

Xylose Lysine Desoxycholate (XLD) Agar

50
Q

Plating Media (Xylose Lysine Desoxycholate)

What is the inhibitor for XLD?

A

Salt and sodium desoxycholate

51
Q

Plating Media (Xylose Lysine Desoxycholate)

What is the pH indicator for XLD?

A

Phenol

52
Q

Environmental Requirements

Aerobic bacteria have the following enzymes: catalase, superoxide dismutase, and peroxidase. What is its cumulative function?

A

Conversion of the toxic form of oxygen (breakdown of hydrogen peroxide into water and oxygen)

53
Q

Environmental Requirements

Most clinically relevant bacteria belong to 3 categories which are?

A
  1. Aerobic
  2. Facultative anaerobes
  3. Obligate anaerobes
54
Q

Environmental Requirements

These organisms: Neisseriaceae, Pseudomonas spp., Brucella, Bordetella, and Francicella all belong to what bacterial category of oxygen and CO2 availability?

A

Aerobes

55
Q

Environmental Requirements

These bacteria can live with or without oxygen

A

Facultative anaerobes

56
Q

Environmental Requirements

These bacteria require very little or no oxygen at all

A

Obligate anaerobes

e.g. Clostridium tetani

57
Q

Environmental Requirements

These are organisms that thrive in the presence of high concentrations of carbon dioxide

A

Capnophilic organisms

58
Q

Environmental Requirements

What is the catalyst for the GASPAK anaerobic jar?

A

Palladium pellets

59
Q

Environmental Requirements

What is the aerobic indicator for the GASPAK anaerobic jar?

A

Methylene blue

60
Q

Environmental Requirements

What is the anaerobic indicator for the GASPAK anaerobic jar?

A

Colorless

61
Q

Environmental Requirements

How many hours does it take to definitively conclude that an anaerobic environment exists in the GASPAK jar (methylene blue indicator)?

A

2 hours

If it’s still blue after 2 hours, then it is not anaerobic

62
Q

Environmental Requirements

This method will consume most of the O2 present inside producing elevated levels of CO2 (used for microaerophilic/capnophilic organisms)

A

Candle Jar

63
Q

Environmental Requirements

In the thioglycollate tube, the turbidity of a tube with obligate aerobes will cluster in what portion of the tube?

A

Top of the tube

64
Q

Environmental Requirements

In the thioglycollate tube, the turbidity of a tube with obligate anaerobes will cluster in what portion of the tube?

A

Bottom of the tube

65
Q

Environmental Requirements

In the thioglycollate tube, the turbidity of a tube with facultataive anaerobes will cluster in what portion of the tube?

A

Throughout the media but more on the top portion

66
Q

Environmental Requirements

In the thioglycollate tube, the turbidity of a tube with aerotolerant anaerobes will cluster in what portion of the tube?

A

Throughout the medium

67
Q

Environmental Requirements

What is the ideal temperature?

A

Body temperature or 37ºC (incubators maintain it at 35-37ºC)

Some require higher (42ºC) while some require lower (20-40ºC)

68
Q

Environmental Requirements

What organism requires a higher temperature (42ºC acc. to the video)?

A

Campylobacter

69
Q

Environmental Requirements

What organism requires a lower temperature (20-40ºC acc. to the video)?

A

Listeria monocytogenes

70
Q

Environmental Requirements

Most clinically relevant bacteria prefer a near neutral pH range, which is?

A

6.5 to 7.5

71
Q

Environmental Requirements

TOF: Abundance of water affects the metabolic pathways in a negative manner

A

False (loss of water; dehyrated media)

72
Q

Environmental Requirements

An increase in solute concentration in the media can lead to what? (2 answers)

A

Osmotic Shock and Cell Lysis

73
Q

Environmental Requirements

Sealing the agar plates is followed by what step?

A

Using humidified incubators

74
Q

Plating Technique

This uses a diluted suspension of cells mixed with melted agar at 50ºC and poured in a petri dish; the diluted suspension contains separated colonies where you can pick a colony of desired type

A

Pour Plate Technique

75
Q

Plating Technique

The suspension is streaked on the surface of the agar plate with a wire loop that is heated in between streaks (most commonly perfomed in the lab)

A

Streak Plate Technique

76
Q

Plating Technique

In Streak Plate Technique, as streaking continues, what happens to the cells?

A

Fewer and fewer cells remain on the wire loop (pinpoint/discrete colonies)

77
Q

Plating Technique

In Streak Plate Technique, this streak may deposit single cells on the agar, which streak is it?

A

Final streak

78
Q

Plating Technique

The volume of a dilute microbial suspension is transferred to the center of the agar plate and is spread evenly using sterile bent rod

Can be used in urine culture but that mostly uses a calibrated wire loop

A

Spread Plate Technique

79
Q

Plating Technique

In Spread Plate Technique, the # of viable colonies equals what?

A

No. of viable organisms

80
Q

Plating Technique

TOF: The Spread Plate Technique cannot be used to count the microbial population

A

False (you can)

81
Q

Isolation of Microorganisms in Pure Culture

There is serial dilution of the sample that will be plated and cultured afterwards but this is less ideal

A

Dilution

Clinical Bacteriology (22 decks)

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