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HSS 1100 > Lecture 3- Diagnostic Microbiology > Flashcards

Lecture 3- Diagnostic Microbiology Flashcards

1
Q

Isolation of pure culture from specimen

A

In order to characterize microorganisms, one must isolated different species from specimen

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2
Q

Culture Media

A

Used to isolate microorganisms

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3
Q

Media type depends on:

A
  • Source of sample tested
  • Species suspected to be in sample
  • Nutritional requirement of suspected organisms
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4
Q

Inoculum

A
  • Small small portion of the sample

- Used to inoculate different media to isolate microorganisms

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5
Q

Methods of Inoculation

A
  • Streak plate method
  • Spread plate method
  • Pour plate method
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6
Q

After inoculation you must..

A

Incubate at 37C (allows organism to multiply and divide)

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7
Q

Colonies

A
  • A few million divided cells, visible to the naked eye
  • Each cell within the colony is the same
  • Colonial morphologies can be used as a mean of distinguishing
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8
Q

Short Term Preservation of Pure Cultures

A
  • Stored in medium refrigeration temperature

- 4 - 10 C

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9
Q

Long Term Preservation of Pure Cultures

A
  • Frozen in liquid nitrogen (-196C)
  • Frozen in special freezer (-70 to -120C)
  • Lyophilization (freeze drying), most stable form for storage.
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10
Q

Identification of Microorganism After Obtaining Pure Culture

A
  • Colonial morphology
    (Form, Elevation and Margin)
  • Cellular morphology (needs microscope)
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11
Q

Resolution

A
  • The ability to distinguish two closely located objects as separate distinct entities
  • fixed by the wavelength of light use and by the optical properties of the lenses
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12
Q

Light Microscope

A

System if lenses used to manipulate the path light beam travels between the specimen and the eye

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13
Q

Electron Microscope

A
  • A beam of electrons controlled by a system of magnetic fields used in place of the light source of a light microscope
  • TEM –> stain with heavy metals
  • SEM –> 3D image
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14
Q

Streak Plate

A
  • Comes directly from specimen
  • Isolates the colonies
  • From one streak to another
  • MOST COMON
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15
Q

Pour Plate

A
  • Place sample inside petrie dish
  • Add liquid agar
  • Problem: Colonies are embedded with the agar
  • Used for enumeration of bacteria
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16
Q

Spread Plate

A
  • Used because you don’t want to know IF, you want to know HOW MUCH
  • Dilutions
  • Spread all over the plate
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17
Q

Staining Techniques

A
  • thin film of specimen (smear) is placed onto a clean microscope slide and let air dry
  • dried smear is fixed by heat to make micro-organisms stick to the glass slide
  • stain with one or more dyes prior to viewing
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18
Q

Simple Staining

A
  • Staining by a single general dye colours all micro-organisms in a specimen
  • Allows the observation of size, shape, number and arrangement of cells
  • Methylene Blue
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19
Q

Differential Staining

A
  • When two or more dyes are used to make observational difference between microbial calls or parts of cells
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20
Q

Differential Staining

Exampls

A
  • Acid fast stain

- Gram stain characterize bacteria into two groups, positive and negative

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21
Q

The Gram Stain

A

1- Flood slide with crystal violet (was with running tap water)
2- Flood with Gram’s iodine (was with water)
3- Carefully decolorize with 95% ethanol (wash with water)
4- Flood with safranin (wash with water) Air Dry

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22
Q

Gram Positive Stain Colours

A

clear, purple, purple, purple, purple

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23
Q

Gram Negative Stain Colours

A

clear, purple, purple, clear, pink

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24
Q

Cell Wall

A
  • Essential for cell growth and division
  • Shape of bacteria related to peptioglycan layer
  • Gram negative usually thinner than gram positive
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25
Q

Gram Positive Cell Wall

A
  • Thick structure made of thick layer of peptidoclycan
  • Teichoic acids often found attached to pep. to give negative charge to help transport positive ions and storage of phosphorus
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26
Q

Gram Negative Celle Wall

A
  • More complex
  • Has outer membran convering a thin layer of peptidogycan (anchored by lipoprotein)
  • LPS is found in the outer layer
  • Outer layer is selective based on size and charge
    MORE HERE
27
Q

Other Stains

A
  • Endospore staining
  • Capsule staining
  • Flagella staining
    MORE HERE
28
Q

Fluorescence Microscopy

A
  • Dye fluoresces at specific wave length
  • Antibodies tagged with dyes are common
    MORE HERE
29
Q

Electron Microscopy

A

The short wavelength of the electron beam. Greater resolving power (0.003um)

Scanning election microscopy
Transmission electron microscopy

30
Q

Importance of studying detailed morphology of micro-organisms

A
  • absence or presence and characteristics of cellular structure help classification
  • morphology of cells helps them respond to environment
31
Q

Bacteria

A
  • Small
  • Higher surface area
  • Higher metabolism
  • Faster growth
  • Replication rate (20 Minutes)
32
Q

Bacterial Shapes

A
  • Spherical cells
  • Cylindrical or rod shapes
  • Spiral or helical shape
33
Q

Spherical cells

A

Round, sometimes ovid

34
Q

Cylindrical or rod shapes

A

Called bacillus, ends can be round square, tapered or pointed

35
Q

Spiral or helical shape

A

Sperillum - corkscrew like shape

36
Q

Chemically Defined

A

Exact composition known

37
Q

Chemically undefined

A

Some component cant be controlled (blood)

38
Q

Agar

A

1.5% used to make solid growth

39
Q

Enrichment media

A
  • Increases # of specific bacteria in sample by favouring growth of interested species
40
Q

Tissue Culture Media

A
  • For cultivating viruses, derived of plant or animal cells
41
Q

Media Requirements

A
  • Bacteria, requirements vary
  • Yeasts, high sugar, low pH
  • Anaerobes
42
Q

Selective Media

A
  • enhance growth of one bacteria or suppression of another
43
Q

Differential Media

A
  • Differentiate bacteria based on their nutritional requirement and phenotypic characteristics
44
Q

MacConkey

A
  • Selective/Differential Media
45
Q

4 Main Conditions Make up Physical Conditions Essential for Successful Cultivation of Micro-organisms

A
  • Temperature
  • Gaseous Atmosphere
  • pH
  • Other
46
Q

Temperature

A
  • Micro-organism can grow over a wider range than complex organisms
47
Q

Optimum Growth Temperature

A
  • Temperature at which a species grows most rapidly
48
Q

Cardinal Temperature

A
  • Minimum
  • Optimal
  • Maximum
  • changes depending on nutritional content of growth media
49
Q

Optimal Temperature

A
  • usually closer to max temp

- at that point enzymes are degraded

50
Q

3 Temperature Groups

A
  • Psychrophiles
  • Mesophiles
  • Thermophiles
51
Q

Psychrophiles

A
  • grow from 15 - 20
  • may die is exposed to room temp
  • found in colder water and soils like oceans and polar regions
  • problem of food spoilage
  • Listeria
52
Q

Mesophiles

A
  • Majority of microorganisms

- 25-40

53
Q

Thermophiles

A
  • 40 - 85 C
  • but grow best between 50-60
  • found in volcanic areas
54
Q

Oxygen requirements

A
  • Aerobic Microorganisms
  • Anaerobic Microoganisms
  • Facultative Microorganism
  • Microareophillic Microorganism
55
Q

Aerobic Microorganisms

A
  • Grow in standard atmospheric pressure (21% oxygen)

- Requires more energy

56
Q

Anaerobic Microoganisms

A
  • Poisoned by oxygen

- Does not use oxygen for energy

57
Q

Facultative Microorganism

A
  • Grows in air atmosphere but can also grow anaerobically

- Does not need oxygen but can use it

58
Q

Microareophillic Microorganism

A
  • Can use oxygen for chemical reactions

- Grow best between 1 and 15% oxygen level

59
Q

pH

A
  • Regardless of external pH, internal pH must remain at 7.5

- Growth observed at pH values of 4-9

60
Q

Water and Light

A

Can be important for certain microorganisms

61
Q

Osmotic Pressure

A
  • Hypotonic
  • Hypertonic
  • Isotonic
62
Q

Antibodies: ELISA Test

A

Direct and Indirect

63
Q

Direct ELISA Test:

Looking for

A
  • More colour, more antigen
  • Good for looking at the antigen
  • Steroid testinging
64
Q

Indirect ELISA Test:

Looking For

A
  • Have you made antibodies against something?
  • more colour, more antibody
  • Pregnancy test

HSS 1100 (9 decks)

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