Chapter 1 (Bacterial Growth) Flashcards
Part 4 (104 cards)
1
Q
It usually refers to reproduction
A
Bacterial growth
2
Q
Majority of bacterial cells reproduce by:
A
binary fission
3
Q
The time required for a cell to divide
A
Generation/doubling time
4
Q
4 basic phases of bacterial growth
A
Lag
Logarithmic/ exponential growth
Stationary or plateau
Death or logarithmic decline
5
Q
Phase of rejuvenescence or physiologic youth
Period of adaptation & little to no division
Cells are NOT dormant
A
Lag
6
Q
At the end of this period, all individual cells usually have lost their reserve storage granules
A
Lag
7
Q
Cellular reproduction is mot active and gen time reaches minimum
Cells are most active metabolically and are most susceptible to adverse conditions
A
Logarithmic/ exponential growth
8
Q
Eventually growth rate slows down that he number of microbial deaths balances the number of new cells and population size stabilizes
Metabolic activity slows down
A
Stationary/ plateau
9
Q
Number of deaths exceeds the number of new cells formed
A
Death/ logarithmic decline
10
Q
Nutritional requirements
A
- Carbon (Autotroph, Heterotroph)
- Nitrogen
- Inorganic Ions (S, P, K, Mg, Cal, Fe, Cu-Mo, Zn)
- Growth factors (B complex, Amino acids, purines + pyrimidines)
11
Q
Require only water, inorganic salts, and CO2 for growth
Can utilize CO2 as their sole source of carbon and synthesize from it the carbon skeletons of all their organic metabolites
A
Autotroph (lithotroph)
12
Q
Unable to utilize CO2 as their sole source of carbon but require that carbon be supplied in an organic form
Require complex organic molecules (glucose as electron donors)
(bacteria pathogenic for man belongs to this group)
A
Heterotroph (organotroph)
13
Q
Utilized by organism in either organic or inorganic form
Used in the synthesis of nucleic acids (DNA, RNA) and proteins
A
Nitrogen
14
Q
Synthesis of sulfur-containing amino acids and vitamins (thiamine and biotin)
A
Sulfur
15
Q
Synthesis of nucleic acids and phospholipids of the CM
A
Phosphorus
16
Q
Cofactors for enzymes
A
K, Mg, Cal
17
Q
They will also stabilize ribosomes, CM, nucleic acids
A
Mg
18
Q
Trace elements used as cofactors for enzymes
A
Fe, Cu-Mo, Zn
19
Q
Function as coenzyme
A
B complex vitamins
20
Q
Manufacture of proteins
A
Amino acids
21
Q
Synthesis of nucleic acids
A
Purines and pyrimidines
22
Q
They are found in the culture medium in the form of yeast extract, whole blood or serum
A
Growth factors
23
Q
Environmental requirements
A
- Oxygen
- Carbon dioxide
- Moisture
- Temperature
- pH
- Ionic strength and osmotic pressure
24
Q
5 groups of organisms based on O2 requirement
A
- Strict aerobes
- Strict anaerobes
- Microaerophiles
- Facultative anaerobes/aerobes
- Aerotolerant anaerobes
25
Require free O2 (molecular O2) to grow
Possess superoxide dismutase and catalase
Strict aerobes
26
Will not grow in the presence of O2 and may actually be killed by its presence
Lack superoxide dismutase
Strict anaerobes
27
Grow only in low levels of O2
Their limited tolerance is probably due to their sensitivity to superoxide free radicals and peroxides
Microaerophiles
28
Can't grow anaerobically and under such conditions, will ferment carbohydrates to form stable fermentation products such as lactic acid, acetic acid
Facultative anaerobes/ aerobes
29
When grown in the presence of air, the organisms change their metabolism to an aerobic one in which carbohydrates are oxidized to water and CO2
Facultative anaerobes/ aerobes
30
Display the Pasteur effect in which the energy needs of the cell are met by consuming less glucose under respiratory metabolism than under a fermentative metabolism
includes most pathogenic bacteria
Facultative anaerobes/ aerobes
31
Will grow in the presence of air but do not posses an oxidative metabolism
Aerotolerant anaerobes
32
Do not use O2 in their metabolism but carry out a fermentative degradation of carbohydrates even in the presence of O2
Aerotolerant anaerobes
33
Posses superoxide dismutase or an equivalent system that neutralizes toxic forms of O2
Aerotolerant anaerobes
34
Certain bacteria will grow best with higher CO2 concentration (5-10%)
Capnophiles
Carbon dioxide
35
The major component of the bacterial cell cytoplasm that also dissolves the food materials in the environment
Major constituent of culture media
Water
36
Leads to evaporation of water content
Incubation
37
Can be deleterious to bacterial growth
Loss of water
38
Water through evaporation is incubation
Moisture
39
Loss of water can cause
less water available for metabolic pathways
40
Relative increase in solute concentration in loss of water
Can osmotically shock the cell causing lysis
41
3 groups based on temp requirement
1. Psychrophilic/cryophilic
2. Mesophilic
3. Thermophilic
42
Cold loving organisms
Naturally found in cold water and soil
Range: -5 - 30C
OT: 10 -20C
Psychrophilic/cryophilic
43
Range: 10-45C
OT: 20-40C
Bacteria pathogenic for man usually grow best 37C
Mesophilic
44
Found in hot springs, rolling compost piles, tropical soils, hot water heaters, hot tubs, thermal vents in the ocean floor
Range: 25-80C
OT: 50-60C
Thermophilic
45
pH range that most clinically relevant bacteria prefer
near neutral (6.5-7.5)
46
What pH is used in preserving food?
Acid pH
47
ex.
V. cholerae grows best in _____
fungi best in _____
9.6
5.0
48
Most bacteria are __________ but are killed or inhibited by high concentrations of salt or sugar
osmotically tolerant
49
Used as a basis in presenting food
ionic strength and osmotic pressure
50
ex.
V. parahaemolyticus needs ____ NaCl
3-7%
51
3 main purpose of Bacterial Cultivation
1. GROW + ISOLATE bacte present in infection
2. DETERMINE WHICH bacte CAUSE, contaminants, colonizers
3. OBTAIN sufficient GROWTH of clinically relevant bacte to allow ID
52
Process of a growing microorganisms by taking bacteria from the infection site by some means of specimen collection and growing them in the artificial environment of the lab
Cultivation
53
Required nutrients for in vitro
Supplied in culture medium
54
Organisms that grow and multiply in or on a culture medium are referred to as
Culture
55
Basis of classification of a culture media
Physical state, composition and use
56
Culture media with antibiotics
Selectively inhibit and may effectively be used for isolating pathogenic species from a mixed population
57
Also act as inhibitors, not only as indicators, of growth for certain bacteria
Dyes
58
Preparing culture
1. Media - dehydrated or tablet form
2. Reconstitute w/ water
3. Agar (heat - water bath/steam - to dissolve)
4. Container (petri dish, test tubes)
59
Solid medium
Provide a large surface area permitting good observation of colonies
Petri dish (plate)
60
Soli, semisolid media
Covered with cotton plug or screw cap
Test tubes
61
When dispensing media into PLATES
media should be STERILIZED FIRST before dispensing into sterile plate
62
When dispensing media into TEST TUBES
STERILIZATION FIRST before dispensing
63
Culture media should be _______ prior to use
STERILE
64
Used for media containing serum or certain proteins
Inspissation
65
Most common of sterilization
Autoclave
66
Ex. for Inspissation
Loeffler's agar
Lowenstein jensen agar
67
Used for carbohydrates solutions and other liquids that may be denatured by heat
Filtration
68
Check for stability
Test QC organisms of known physiologic and biochemical properties
Quality control
69
Storage to prevent deterioration and dehydration of media
Refrigeration
70
Culture media taken from the refrigerator must be _____________ before use
come to room temp
71
Process of bacterial cultivation
1. Inoculation
2. Incubation
3. Inspection of cultures
72
Implantation or introduction of specimen into the culture/medium
Inoculation
73
Instruments for inoculation
- sterile cotton swab
- inoculating wire loop/needle
74
Refers to the material used to initiate a new culture of microorganisms or cell
Inoculum
75
Process of inoculation
SPECIMEN
|
liquid medium
|
(suspend,mix)
solid medium
|
streak, stab, stab & streak
76
Provide the proper temperature and ventilation
Incubation
77
Incubation is usually for a period of
18-24 hrs
78
Inspection of cultures indications
1. growth in a broth
2. growth on a solid medium
79
Indications of growth in a broth
- turbidity
- change in color
- gas bubbles
80
Indications of growth on solid medium
Colony
81
What do you call bacteria that have multiplied will cling together to form a visible mass?
Colony
82
Criteria frequently used to characterize bacterial colony:
- Size
- Pigmentation
- Shape
- Surface appearance
- Consistency and texture
- Changes in agar media
- Odor
83
Relative terms aside from mm for Size
pinpoint
- small
- medium
- large
84
Forms in shapes of a colony
- punctiform
- circular (round)
- filamentous
- irregular
- rhizoid
85
Elevations in shape in a colony
- flat
- raised
- convex
- umbonate
- crateriform
- Draughtsman colony
86
Margin in shape in a colony
- entire
- irregular
- lobate
- scalloped
- filiform
- undulate
- curled
- serrate
87
Surface appearance of a colony
- glistening
- dull
- translucent
- opaque
88
Consistency and texture of a colony
1. Dry and friable
2. Viscous
3. Smooth
4. Mucoid
5. Rough
89
Colony when touched by needle, can be pushed around the surface of the medium
Dry and friable
90
Viscous cell mass clings to wire when touched and stringing away from the colony is observed when wire is withdrawn
Viscid
91
Smooth, glistening and appears homogenous
Smooth
92
Waterlike, glistening confluent, appearance, which is characteristic of organisms forming slime layer or capsule
Mucoid
93
Surface may be striated or granular
Rough
94
Changes in agar media
- hemolytic pattern on BA
- changes in the color of the pH
- pitting of agar surface
95
Certain bacteria produce distinct odors that can be helpful in their preliminary ID
Odor
96
If use is to make an accurate ID of disease-causing organisms,
PURE CULTURE
97
Pure cultures are obtained with the use of
SOLID MEDIUM
98
Methods of obtaining pure (axenic) culture
1. Streak plate
2. Pour plate or spread plate
99
The probably the most practical and most useful method of obtaining discrete/isolated colonies and pure culture
Streak plate
100
If the specimen contains only ONE SPECIMEN
a pure culture will obtained AFTER INCUBTION of primary plates
101
If specimen has a MIXED POPULATION
a pure culture will only be obtained UPON, subculture of a single isolated colony form the primary plate
102
Streak plate methods
1. Simple streaking
2. Multiple interrupted streaking
3. 4 Quadrant streaking
103
Generally used as a mean of determining the approximate number of viable organisms in a liquid (water or milk)
Consists of the preparation of a series of dilutions of the specimen
Pour plate or spread plate
104
Pour plate/ spread plate express the number of colony as
colony forming units (CFU) per ml
