Practical 3 Flashcards

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1
Q

Define obligate intracellular parasite

A

Must go inside a living host organism to replicate

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2
Q

A virus that infects bacteria

A

Bacteriophage

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3
Q

Must go inside a living host organism to replicate

A

Obligate intracellular parasite

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4
Q

How does a medium used for bacterial growth differ from media used for bacteriophage growth?

A

Ordinary agar or broth media is suitable for growing bacterial cultures. Bacteria growing in lab media can serve as the host cell for growing viruses that infect bacteria.

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5
Q

What is the purpose of making serial dilutions of the T4 phage?

A

To obtain a countable plate in which 30-300 individual plaques

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6
Q

What is a viral plaque and what does it represent?

A

A plaque is an area of clearing in a confluent lawn of bacterial growth. A plaque represents the spot where a virus has landed, infected the bacteria it encountered, and lysed them.

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7
Q

What purpose does the E. coli serve in this procedure (Viral Plaque Assay)?

A

E.coli serves as the host cell for the T4 bacteriophage

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8
Q

The purpose of a viral plaque assay is to determine the number of bacteriophage in a sample. True or false?

A

True

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9
Q

A plaque represents where the E. coli have replicated from one cell into millions of cells

A

False

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10
Q

PFU stands for “plaque forming units”.

A

True

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11
Q

PFU

A

Plaque forming units

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12
Q

What is considered a countable # of plaques

A

30-300

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13
Q

Viruses that burst the host cell and kill them are called

A

Lytic viruses

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14
Q

Lytic viruses burst open their bacterial host cell once the appropriate number of viruses has been synthesized

A

True

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15
Q

Study of fungus

A

Mycology

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16
Q

What kind of organisms are fungi?

A

Eukaryotic organism

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17
Q

Dimorphic fungi

A

Grows as yeast or mold depending on the environment

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18
Q

What type of media is used to grow fungi?

A

Sabouraud’s Agar

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19
Q

What is speical about Sabouraud’s Agar?

A

Simple nutrients (gluocose and peptone)
pH of 4.5-5.6

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20
Q

What pH inhibits bacterial growth?

A

4.5-5.6

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21
Q

Microscopically, yeast cells are

A

unicellular and round to oval

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22
Q

Fungi that grow as mold produce

A

Multicellular filaments called hyphae

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22
Q

Asexual spores produced by molds

A

Sporangiospores
Conidiospores

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23
Q

Explain why Coccidioides immitis is a dimorphic fungus?

A

It can grow as a yeast or mold depending on environmental conditions

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24
Q

What are the growth differences between fungus and bacteria?

A

Fungi grow slower, at a lower temperature, and a lower pH

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25
Q

Define blastospore

A

Asexual reproductive forms of yeast that bud from parent cell

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26
Q

Define pseudohyphae

A

Successive blastospores remaining attached to the original parent cell

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27
Q

Successive blastospores remaining attached to the original parent cell

A

Pseuodohyphae

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28
Q

Asexual reproductive forms of yeast that bud from parent cell

A

Blastospore

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29
Q

Define septate hyphae

A

Fungal hyphae filaments separated by a cross wall

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30
Q

Fungal hyphae filaments separated by a cross wall

A

Define septate hyphae

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31
Q

Explain the difference between vegetative hyphae and aerial hyphae

A

Vegetative hyphae grow on or down into the agar surface to extract nutrients from the medium. Aerial hyphae grow above the agar surface

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32
Q

grow on or down into the agar surface to extract nutrients from the medium.

A

Vegetative hyphae

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33
Q

grow above the agar surface

A

Aerial hyphae

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34
Q

inside a sac-like structure.

A

Sporangiospores

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35
Q

are formed on hyphae and may be single or multicelled.

A

Conidiospores

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36
Q

Difference between sporangiospores and conidiospores

A

Sporangiospores are inside a sac-like structure. Conidiospores are formed on hyphae and may be single or multicelled.

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37
Q

Asexual reproductive spores are produced by ____ hyphae

A

Aerial hyphae

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38
Q

Two types of asexual spores are

A

Sporangiospores and Conidiospores

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39
Q

Saccharomyces and Candidia are ____ while
Penicillium, Rhizopus, and Aspergillus are _____

A

Yeast
Mold

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40
Q

What is the plaque equation?

A

Plaque count X Plate Dilution x 10 (if you plated 0.1 ml)

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41
Q

Staphylococcus and Micrococcus are catalase positive

A

True

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42
Q

Staphylococcus and Micrococcus are Gram (Blank)

A

Positive

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43
Q

Staphylococcus epidermidis can be an opportunist

A

True

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44
Q

Staphylococcus and Micrococcus grow in

A

Clusters

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45
Q

Streptococcus pneumoniae mostly causes

A

Middle ear infections

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46
Q

Group A Streptococcus

A

cause ninety percent of acute streptococcal infections in humans. It is the cause of “strep throat”

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47
Q

Streptococcus mutans is

A

another viridans streptococcus associated with dental caries and plaque.

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48
Q

Streptococcus can/cannot produce catalse?

A

Cannot (negative)

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49
Q

Streptococcus grows in

A

pairs or chains

50
Q
  1. Alpha Hemolysis
A

a partial damage of the red blood cells which reduces the hemoglobin to methemoglobin. This partial damage is shown as an olive green to brown discoloration in the media surrounding the bacterial colony on the blood agar.

51
Q
  1. Beta Hemolysis
    ex: S. pyogenes + Group C Strep.
A

a complete lysing of the red blood cells. This is demonstrated by a complete clearing of the red blood cells in the media around a colony leaving only the color of the base (TSA) media.

52
Q
  1. Gamma Hemolysis
A

the lack of hemolysis. There is no damage to the red blood cells in the media.

53
Q

Rhizopus mold looks

A

White on top and bottom
Cottony
Like a tootsie pop

54
Q

Identifiy this mold

A

Aspergillus
-Black on top
-Reverse pigment is yellow
-Velvetty (medium)
-Aerial Hyphae
-Dandelion

55
Q

Identify this mold

A

Penicillium
-Green on top
-Reverse pigment is yellow
-Wooly texture (low)
-Skeleton hands

56
Q

Yeast from macro looks

A

Moist, white, creamy, pearl-like colonies

57
Q

Mold from macro looks

A

Fuzzy

58
Q

Mold from micro looks

A

Hyphae + Spores

59
Q

Yeast microscopically are

A

Oval shaped and bigger than bacteria

60
Q

People who harbor a pathogen but exhibit no symptoms

A

Define carrier

61
Q

Define MRSA

A

Methicillin resistant Staphylococcus aureus

62
Q

Which genus and species of staphylococcus or micrococcus is coagulase positive?

A

Staphylococcus aureus

63
Q

The strains of Staph and Micro:

A

Staphylococcus: auereus + epidermidis
Micrococcus: roseus + luteus

64
Q

What Staph bacteria are SALT TOLERANT on mannitol salt
(Staph + Micro)

A

Staphylococcus aureus
Staphylococcus epidermidis

65
Q

What bacteria are positive for MANNITOL FERMENTATION (turned yellow)?
(Staph + Micro)

A

ONLY Staphylococcus aureus

66
Q

What bacteria are SALT TOLERANT?

A

Staphylococcus auereus
Staphylococcus epidermidis

67
Q

What bacteria produce a + in NITRATE REDUCTION? (red color change)

A

Staphyloccocus aureus
Staphyloccous epidermidis
Micrococcus roseus

68
Q

Virulent

A

Extreme disease causing

69
Q

3 diseases that Staphyloccocus aureus can cause are

A

Toxic shock syndrome
Wound infections
Food poisoning

st

70
Q

Coagulase is an enzyme produced by both Staphylococcus aureus and Staphylococcus epidermidis

A

False, only S. aureus

71
Q

A mannitol positive colony on mannitol salt agar is indicated by the presence of a pink color around the colony

A

False

72
Q

Micrococcus and Staphylococcus can grow equally well on media that contains 7.5% salt

A

False

73
Q

Streptococcaceae family includes:

A

Streptococcus: sanguinis + pneumoniae + pyogenes + Group C
Enterococcus: faecalis

74
Q

They are differentiated from Staphylococcus and Micrococcus by the _____ reaction. The Streptococcaceae cannot produce ________.

A

Catalase; catalase

75
Q

Streptococcus and Enterococcus are Gram-positive cocci in ______ or ______ when stained from a broth.

A

Pairs; chains

76
Q

Some bacteria produce hemolysins that damage the membrane of red blood cells.

A

Hemolysis

77
Q

________________ colonies are larger, convex, opaque, and frequently pigmented.
________________ colonies are smaller, often translucent to semi-opaque.

A

Staphylococcus; Streptococcus

78
Q

________________ colonies are larger, convex, opaque, and frequently pigmented.
________________ colonies are smaller, often translucent to semi-opaque.

A

Staphylococcus; Streptococcus

79
Q

Which enzyme helps differentiate all Staph from Strep

A

Catalase

80
Q

The principle and reagant used in catalase and coagulse test?

A

Principle: does the bacteria produce the enzyme?
Catalse reagant: hydrogen peroxide
Coagulase reagent: rabbit plasma

81
Q

Staphylococcus aureus + epidermidis COAGULASE test result:

A

Aureus: +
Epidermidis: -

82
Q

Staphylococcus aureus + epidermidis MANNITOAL SALT and FERMENTATION test result:

A

Growth on salt: aureus + epidermidis
Fermentation of Mannitol: aureus

83
Q

Nitrate + or -
Staph and Micro microbes

A

+: aureus, epidermidis, roseus
-: Micrococcus luteus

84
Q

Do Enterobacteriacieae Ferment Glucose?

A

Yes

85
Q

Enterobacteriaceae do not ferment glucose. T or F?

A

False

86
Q

MacConkey Agar is…

A

is a selective and differential media
It is used to grow Gram-negative bacilli and differentiate their ability to ferment lactose.

Has Bile Salts + Crystal Violet Dye

87
Q

Are Enterobacteriaceae are gram + or -

A

Gram negative bacilli

88
Q

What organisms are Alpha Streptoccocus and Optochin Sensitive?

A

Alpha: S. sanguinis + S. pneumoniae
Resistant: S. sanguinis (negative)
Sensitive: S. pneumoniae (positive)

89
Q

What organisms are Beta Streptococcus and A or C Group

A

Beta: S. pyogenes + Group C Strep.
A: Streptococcus Pyogenes
C: Group C Streptococcus

90
Q

Test results for ability to hydrolyze Bile Esculin
ex: Enterococcus faecalis

A

+: brown/black media
-: no color change

91
Q

What does glucos fermenation look like?

A

Yellow: + positive
Red: - negative (no color change)

92
Q

Identify this macroscopically and describe it

A

Aspergillus mold
-Black
-Velvetty
-AERIAL hyphae
-YELLOW reverse pigment

93
Q

Identify this microscopically

A

Aspergillus mold

94
Q

Identify this macroscopically and describe it

A

Penicillium mold
-Green on top
-WOOLY texture
-YELLOW reverse pigment

95
Q

Identify this microscopically

A

Penicillium mold

96
Q

Identify this macroscopically and describe it

A

Rhizopus
-White on top + bottom (reverse pigment)
-COTTONY

97
Q

Identify this microscopically

A

Rhizopus
-Looks like tootsie roll or tootsie pop

98
Q

What is an “enteric” organism?

A

Normal flora of the gastrointestinal tract

99
Q

Motility media is inoculated with an inoculating loop

A

False, inoculating wire

100
Q

In an organism can use citrate as its sole carbon source the media will appear what color?

A

Blue

101
Q

Enterobacteriaceae are the most frequently encountered microbes in the clinical microbiology laboratory

A

True

102
Q

This enzyme catabolized tryptone into indole and pyruvic acid

A

tryptophanase.

103
Q

If urease is present the pH of the culture media will decrease

A

False

104
Q

Which organisms must be stored in a candle jar because they’re microaerophiles?

A

Some Streptococcus

105
Q

Only grows Gram + bacteria:
Determines Hemolytic Properties
Contains: Antibiotic + Acid

A

CNA (blood) Agar

106
Q

Test results of MacConkey Agar:

A

Growth on media = Gram-negative bacilli

***Determine the ability to ferment lactose:

Hot Pink colonies= Positive for lactose fermentation

Clear colonies = Negative for lactose fermentation

107
Q

How does MacConkey Agar Select for Gram- bacteria

A

Inhibiting growth by using bile salts and CV dye
Fermentation of lactose will be pink

108
Q

The truly enteric pathogens in the Enterobacteriaceae family include:

A

Salmonella: typhoid fever
Shigella: bacterial dysentery

109
Q

How are culture media designed to detect if bacteria can produce a specific enzyme?

A

Substrates are incorporsted into the media along with an indicator system to detect products

110
Q

What is the substrate of the MRVP test?

A

Glucose

111
Q

What is the substrate of the indole test?

A

Tryptone

112
Q

Name three Enterobacteriaceae normally found in the gastrointestinal tract

A

Escherichia coli, Enterobacter, Klebsiella

113
Q

Name one of many commercial test systems used to identify Gram negative bacilli in clinical labs

A

API20E
Enterotube

114
Q

What are the two major groups of Gram-negative bacilli and what are the common characteristics of each group?

A

Enterobacteriaceae ferment glucose and do not produce oxidase. Nonenterobacteriaceae (non fermenters) do not ferment glucose and many are oxidase positive

115
Q

What carbohydrates are in the Kligler Iron Agar media?

A

Glucose and lactose

116
Q

Why is MacConkey agar considered a selective and differential media?

A

It contains bile salts and crystal violet that inhibit the growth of Gram positive bacteria therefore selecting for Gram negative bacteria. It contain lactose and differentiates based on lactose fermentation

117
Q

Nitrate broth is used to determine

A

an organism can reduce nitrate

118
Q

How did Lancefield divide the beta-hemolytic streptococci into groups?

A

Based on the C polysaccharide extracted from the cell walls

119
Q

What is the species name of Lancefield Group B streptococci?

A

Streptococcus agalactiae

120
Q

Define VRE

A

vancomycin resistant Enterococcus

121
Q

Has been recognized as potentially dangerousfor newborn Babies

A

Beta-hemolytic Group B Streptococcus

122
Q

The cause of “strep throat” “ach”

A

Beta-hemolytic Group A Streptococcus