Practical 3 Flashcards
(123 cards)
1
Q
Define obligate intracellular parasite
A
Must go inside a living host organism to replicate
2
Q
A virus that infects bacteria
A
Bacteriophage
3
Q
Must go inside a living host organism to replicate
A
Obligate intracellular parasite
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.
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
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.
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
8
Q
The purpose of a viral plaque assay is to determine the number of bacteriophage in a sample. True or false?
A
True
9
Q
A plaque represents where the E. coli have replicated from one cell into millions of cells
A
False
10
Q
PFU stands for “plaque forming units”.
A
True
11
Q
PFU
A
Plaque forming units
12
Q
What is considered a countable # of plaques
A
30-300
13
Q
Viruses that burst the host cell and kill them are called
A
Lytic viruses
14
Q
Lytic viruses burst open their bacterial host cell once the appropriate number of viruses has been synthesized
A
True
15
Q
Study of fungus
A
Mycology
16
Q
What kind of organisms are fungi?
A
Eukaryotic organism
17
Q
Dimorphic fungi
A
Grows as yeast or mold depending on the environment
18
Q
What type of media is used to grow fungi?
A
Sabouraud’s Agar
19
Q
What is speical about Sabouraud’s Agar?
A
Simple nutrients (gluocose and peptone)
pH of 4.5-5.6
20
Q
What pH inhibits bacterial growth?
A
4.5-5.6
21
Q
Microscopically, yeast cells are
A
unicellular and round to oval
22
Q
Fungi that grow as mold produce
A
Multicellular filaments called hyphae
22
Q
Asexual spores produced by molds
A
Sporangiospores
Conidiospores
23
Q
Explain why Coccidioides immitis is a dimorphic fungus?
A
It can grow as a yeast or mold depending on environmental conditions
24
What are the growth differences between fungus and bacteria?
Fungi grow slower, at a lower temperature, and a lower pH
25
Define blastospore
Asexual reproductive forms of yeast that bud from parent cell
26
Define pseudohyphae
Successive blastospores remaining attached to the original parent cell
27
Successive blastospores remaining attached to the original parent cell
Pseuodohyphae
28
Asexual reproductive forms of yeast that bud from parent cell
Blastospore
29
Define septate hyphae
Fungal hyphae filaments separated by a cross wall
30
Fungal hyphae filaments separated by a cross wall
Define septate hyphae
31
Explain the difference between vegetative hyphae and aerial hyphae
Vegetative hyphae grow on or down into the agar surface to extract nutrients from the medium. Aerial hyphae grow above the agar surface
32
grow on or down into the agar surface to extract nutrients from the medium.
Vegetative hyphae
33
grow above the agar surface
Aerial hyphae
34
inside a sac-like structure.
Sporangiospores
35
are formed on hyphae and may be single or multicelled.
Conidiospores
36
Difference between sporangiospores and conidiospores
Sporangiospores are inside a sac-like structure. Conidiospores are formed on hyphae and may be single or multicelled.
37
Asexual reproductive spores are produced by ____ hyphae
Aerial hyphae
38
Two types of asexual spores are
Sporangiospores and Conidiospores
39
*Saccharomyces* and *Candidia* are ____ while
Penicillium, Rhizopus, and Aspergillus are _____
Yeast
Mold
40
What is the plaque equation?
Plaque count X Plate Dilution x 10 (if you plated 0.1 ml)
41
Staphylococcus and Micrococcus are catalase positive
True
42
Staphylococcus and Micrococcus are Gram (Blank)
Positive
43
Staphylococcus epidermidis can be an opportunist
True
44
Staphylococcus and Micrococcus grow in
Clusters
45
Streptococcus pneumoniae mostly causes
Middle ear infections
46
Group A Streptococcus
cause ninety percent of acute streptococcal infections in humans. It is the cause of “strep throat”
47
Streptococcus mutans is
another viridans streptococcus associated with dental caries and plaque.
48
Streptococcus can/cannot produce catalse?
Cannot (negative)
49
Streptococcus grows in
pairs or chains
50
2. Alpha Hemolysis
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
1. **Beta** Hemolysis
ex: S. pyogenes + Group C Strep.
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
3. Gamma Hemolysis
the lack of hemolysis. There is no damage to the red blood cells in the media.
53
Rhizopus mold looks
White on top and bottom
Cottony
Like a tootsie pop
54
Identifiy this mold
**Aspergillus**
-Black on top
-Reverse pigment is yellow
-Velvetty (medium)
-Aerial Hyphae
-Dandelion
55
Identify this mold
**Penicillium**
-Green on top
-Reverse pigment is yellow
-Wooly texture (low)
-Skeleton hands
56
Yeast from macro looks
Moist, white, creamy, pearl-like colonies
57
Mold from macro looks
Fuzzy
58
Mold from micro looks
Hyphae + Spores
59
Yeast microscopically are
Oval shaped and bigger than bacteria
60
People who harbor a pathogen but exhibit no symptoms
Define carrier
61
Define MRSA
Methicillin resistant Staphylococcus aureus
62
Which genus and species of staphylococcus or micrococcus is coagulase positive?
Staphylococcus aureus
63
The strains of Staph and Micro:
Staphylococcus: auereus + epidermidis
Micrococcus: roseus + luteus
64
What Staph bacteria are SALT TOLERANT on mannitol salt
(Staph + Micro)
Staphylococcus aureus
Staphylococcus epidermidis
65
What bacteria are positive for MANNITOL FERMENTATION (turned yellow)?
(Staph + Micro)
ONLY Staphylococcus aureus
66
What bacteria are SALT TOLERANT?
Staphylococcus auereus
Staphylococcus epidermidis
67
What bacteria produce a + in NITRATE REDUCTION? (red color change)
Staphyloccocus aureus
Staphyloccous epidermidis
Micrococcus roseus
68
Virulent
Extreme disease causing
69
3 diseases that Staphyloccocus aureus can cause are
Toxic shock syndrome
Wound infections
Food poisoning
## Footnote
st
70
Coagulase is an enzyme produced by both Staphylococcus aureus and Staphylococcus epidermidis
False, only S. aureus
71
A mannitol positive colony on mannitol salt agar is indicated by the presence of a pink color around the colony
False
72
Micrococcus and Staphylococcus can grow equally well on media that contains 7.5% salt
False
73
Streptococcaceae family includes:
Streptococcus: sanguinis + pneumoniae + pyogenes + Group C
Enterococcus: faecalis
74
They are differentiated from Staphylococcus and Micrococcus by the _____ reaction. The Streptococcaceae cannot produce ________.
Catalase; catalase
75
Streptococcus and Enterococcus are Gram-positive cocci in ______ or ______ when stained from a broth.
Pairs; chains
76
Some bacteria produce hemolysins that damage the membrane of red blood cells.
Hemolysis
77
________________ colonies are larger, convex, opaque, and frequently pigmented.
________________ colonies are smaller, often translucent to semi-opaque.
Staphylococcus; Streptococcus
78
________________ colonies are larger, convex, opaque, and frequently pigmented.
________________ colonies are smaller, often translucent to semi-opaque.
Staphylococcus; Streptococcus
79
Which enzyme helps differentiate all Staph from Strep
Catalase
80
The principle and reagant used in catalase and coagulse test?
Principle: does the bacteria produce the enzyme?
Catalse reagant: hydrogen peroxide
Coagulase reagent: rabbit plasma
81
Staphylococcus aureus + epidermidis COAGULASE test result:
Aureus: +
Epidermidis: -
82
Staphylococcus aureus + epidermidis MANNITOAL SALT and FERMENTATION test result:
Growth on salt: aureus + epidermidis
Fermentation of Mannitol: aureus
83
Nitrate + or -
Staph and Micro microbes
**+**: aureus, epidermidis, roseus
**-**: *Micrococcus luteus*
84
Do Enterobacteriacieae **Ferment Glucose?**
Yes
85
Enterobacteriaceae do not ferment glucose. T or F?
False
86
MacConkey Agar is...
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
Are Enterobacteriaceae are gram + or -
Gram negative bacilli
88
What organisms are **Alpha** Streptoccocus and **Optochin Sensitive?**
Alpha: S. sanguinis + S. pneumoniae
Resistant: S. sanguinis (negative)
Sensitive: S. pneumoniae (positive)
89
What organisms are Beta Streptococcus and A or C Group
**Beta:** S. pyogenes + Group C Strep.
**A: Streptococcus Pyogenes
C: Group C Streptococcus**
90
Test results for ability to hydrolyze **Bile Esculin**
ex: **Enterococcus faecalis**
+: brown/black media
-: no color change
91
What does glucos fermenation look like?
Yellow: + positive
Red: - negative (no color change)
92
Identify this macroscopically and describe it
Aspergillus mold
-Black
-Velvetty
-AERIAL hyphae
-YELLOW reverse pigment
93
Identify this microscopically
Aspergillus mold
94
Identify this macroscopically and describe it
Penicillium mold
-Green on top
-WOOLY texture
-YELLOW reverse pigment
95
Identify this microscopically
Penicillium mold
96
Identify this macroscopically and describe it
Rhizopus
-White on top + bottom (reverse pigment)
-COTTONY
97
Identify this microscopically
Rhizopus
-Looks like tootsie roll or tootsie pop
98
What is an “enteric” organism?
Normal flora of the gastrointestinal tract
99
Motility media is inoculated with an inoculating loop
False, inoculating wire
100
In an organism can use citrate as its sole carbon source the media will appear what color?
Blue
101
Enterobacteriaceae are the most frequently encountered microbes in the clinical microbiology laboratory
True
102
This enzyme catabolized tryptone into indole and pyruvic acid
tryptophanase.
103
If urease is present the pH of the culture media will decrease
False
104
Which organisms must be stored in a candle jar because they're microaerophiles?
Some Streptococcus
105
Only grows **Gram +** bacteria:
Determines Hemolytic Properties
Contains: **Antibiotic + Acid**
CNA (blood) Agar
106
Test results of MacConkey Agar:
**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
How does **MacConkey Agar Select for Gram-** bacteria
Inhibiting growth by using bile salts and CV dye
Fermentation of lactose will be pink
108
The truly enteric pathogens in the Enterobacteriaceae family include:
Salmonella: typhoid fever
Shigella: bacterial dysentery
109
How are culture media designed to detect if bacteria can produce a specific enzyme?
Substrates are incorporsted into the media along with an indicator system to detect products
110
What is the substrate of the MRVP test?
Glucose
111
What is the substrate of the indole test?
Tryptone
112
Name three Enterobacteriaceae normally found in the gastrointestinal tract
Escherichia coli, Enterobacter, Klebsiella
113
Name one of many commercial test systems used to identify Gram negative bacilli in clinical labs
API20E
Enterotube
114
What are the two major groups of Gram-negative bacilli and what are the common characteristics of each group?
Enterobacteriaceae ferment glucose and do not produce oxidase. Nonenterobacteriaceae (non fermenters) do not ferment glucose and many are oxidase positive
115
What carbohydrates are in the Kligler Iron Agar media?
Glucose and lactose
116
Why is MacConkey agar considered a selective and differential media?
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
Nitrate broth is used to determine
an organism can reduce nitrate
118
How did Lancefield divide the beta-hemolytic streptococci into groups?
Based on the C polysaccharide extracted from the cell walls
119
What is the species name of Lancefield Group B streptococci?
Streptococcus **agalactiae**
120
Define VRE
vancomycin resistant Enterococcus
121
Has been recognized as potentially dangerousfor newborn **B**abies
**B**eta-hemolytic Group **B** Streptococcus
122
The cause of “strep throat” "**a**ch"
Beta-hemolytic Group **A** Streptococcus
