Chapter 3 Flashcards
(133 cards)
1
Q
population of bacteria grown in the laboratory is referred to as
A
culture
2
Q
contains only one single type of bacteria
A
pure culture
3
Q
bacterial cultures must be periodically transferred to new media to keep the bacterial population growing
A
subcultured
4
Q
means using practices and procedures to prevent contamination from pathogens. It involves applying the strictest rules to minimize the risk of infection.
A
aseptic technique
5
Q
Indications for various culture methods
A
- Isolate bacteria in pure culture and identify the same by performing various tests.
- Demonstrate biochemical, antigenic, and other phenotypic and genomic
properties of the isolated colonies. - Demonstrate susceptibility of the isolated bacteria to antibiotics, bacteriophages, bacteriocins, etc.
- Prepare antigens for various uses.
- Maintain stock culture. 6. Estimate viable counts.
6
Q
most effective way to isolate a single type of bacteria from a source that contains many by diluting the individual cells by
spreading them over the surface of an agar plate using a platinum or inoculating
loop of 2–4 mm diameter
A
streak plate method
7
Q
piles of bacterial cells observed after an incubation period are called
A
colonies
8
Q
Lawn culture method is used for (3)
A
(a) Antibiotic susceptibility testing by disk diffusion method
(b) Bacteriophage typing
(c) For preparation of bacterial antigens and vaccines
9
Q
prepared by flooding the surface of the plate with a liquid culture or suspension of the bacterium, pipetting off the excess inoculum and incubating the plate
A
lawn culture
10
Q
Stab culture is used for (4)
A
(a) mainly for demonstration of gelatin
liquefaction
(b) demonstration of oxygen requirement of the bacterium under
study
(c) for the maintenance of stock cultures
(d) to study motility of bacteria in
semisolid agar
11
Q
used to determine approximate
number of viable organisms in liquids, such as water or urine
A
pour plate culture
12
Q
a deep culture of agar or gelatin through which the inoculum is evenly distributed by shaking before the medium is solidified and which is used chiefly for the demonstration of anaerobic colonies
A
shake culture
13
Q
liquid culture is used for (3)
A
(a) blood culture and for sterility
(b) dilution in the medium
(c) large yields culture
14
Q
does not provide a pure culture from mixed inocula—the major disadvantage, nor identify a bacteria
A
Liquid culture
15
Q
examples of organisms that grow better in air supplemented with 5-10 % CO2
A
Pneumococcus and gonococcus
16
Q
a method routinely employed in clinical bacteriology and enables the isolation of distinct colonies which may be picked out, if necessary for further purification and study
A
Surface Plating
17
Q
majority of organisms likely to be associated with those for which the media are used will not grow, and the isolation of pure cultures is thus facilitated
A
selective media
18
Q
media such as selenite broth for Salmonella sp, favor the multiplication of particular species as a step towards their isolation in pure culture
A
enrichment media
19
Q
media, such as Willis and Hobbs medium for Clostridium sp, contain ingredients that change in appearance with particular
organisms and so assist their isolation
A
indicator media
20
Q
What are the two forms in selective treatment of the specimen before culture?
A
i. Heating at 65°C for 30 minutes or at higher temperatures for shorter period
i. Heating at 65°C for 30 minutes or at higher temperatures for shorter period
21
Q
This consists of a tube of semisolid agar, with a narrow tube open at both ends placed in the center of the medium in such a way that it projects above the level of the agar
A
cragie’s tube
22
Q
Pathogenic bacteria may be isolated from mixtures by inoculation into appropriate animals due to the fact that laboratory animals are highly susceptible to certain organisms for example, the mouse to the pneumococcus
A
animal inoculation
23
Q
Elements of aseptic environment
A
- Quiet area
- Work surface
- Personal Hygiene
- Reagents media
- Cultures
24
Q
Sterile Handling
A
- swabing
- capping
- flaming
- handling bottles and flasks
- pippeting
- pouring
25
air blows from the side facing you, parallel to the work surface, and
not circulated
horizontal safety cabinet
26
air blows down from the top of the hood onto the
work surface and is drawn through the work surface and either recirculated or vented
vertical safety cabinets
27
major source of contamination
humidified incubators
28
suggested agar as a base for culture media
Fannie Eilshemius Hesse
29
developed the pour plate method and was the first to use solid culture media
for culture of bacteria
Robert Koch
30
developed petri dish
Richard Petri
31
A nutrient material prepared for the growth of microorganisms in a
laboratory
culture medium
32
microbes are introduced into a culture medium to initiate growth
inoculum
33
microbes that grow and multiply in or on a culture medium
culture
34
process of growing microorganisms in culture by taking bacteria
from the infection site (i.e. in vivo environment) by some means of specimen
collection and growing them in the artificial environment of the laboratory (i.e. the in
vitro environment)
cultivation
35
laboratory culture containing a single species of organism
pure culture
36
What are the different purposes of bacterial cultivation?
1. Grow and isolate all bacteria present in an infection.
2. Infection and contaminants or colonizers: To determine which of the bacteria that
grow are most likely causing infection and which are likely contaminants or
colonizers.
3. Identification and characterization.
37
Tap water with low mineral content is often suitable for culture media. What is the best used water for culture media?
glass-distilled or demineralized water
38
agar is derived from?
seaweed
39
complex mixture of partially digested proteins
peptone
40
does not add to the nutritive properties of a medium and is not affected by the growth of bacteria
agar
41
contains a wide range of amino acids, growth factors and inorganic salts
yeast extract
42
used mainly as a comprehensive source of growth factors and may be substituted for meat extract in culture media
yeast extract
43
consists mainly of maltose (about 50%), starch, dextrins and glucose, and contains about 5 percent of proteins and protein breakdown products, and a wide range of mineral salts and growth factors
malt extract
44
used for enriching culture media
blood and serum
45
Used for obtaining bacterial growth from blood or water when large volumes have to be tested, and for preparing bulk cultures of antigens or vaccines
liquid (broth) media
46
made by adding a solidifying agent to
the nutrients and water
solid agar media
47
most common solidifying agent
agarose
48
For special purposes where agar is added to media in concentrations that are too low to solidify them. At 0.2 to 0.5 percent it yields a semisolid medium through which motile, but not non motile, bacteria may spread
semisolid media
49
include nutrient broth and peptone water, which form the basis of other media
simple (basal) media
50
an example of a simple liquid medium that consists of peptone, meat extract, sodium chloride, and water
nutrient broth
51
an example of a simple solid medium. The medium is used routinely for isolation of many bacteria from clinical specimens
nutrient agar
52
media that contain some ingredients of unknown
chemical composition
complex media
53
a synthetic kind of medium which contains known quantities of all
ingredients used but does not contain any animal, yeast, or plant tissue
defined media
54
Defined media consists of?
(1) Trace elements and vitamins
(2) A defined carbon source and nitrogen source required by certain microbes
55
invariably solid media that facilitate growth of certain fastidious bacteria. These media are prepared by adding substances like blood, serum, and egg to the basal media in order to meet the nutritional requirements of more exacting and more fastidious bacteria
enriched media
56
Give examples of enriched media.
Blood agar, chocolate agar, Loeffler’s serum slope
57
liquid media that stimulate the growth of certain bacteria or suppress the growth of others for isolation of desired pathogenic bacteria
enrichment media
58
selenite-F broth or tetrathionate broth) are used for the isolation of?
Salmonella typhi, Shigella spp. from feces
59
solid media that contain substances that inhibit the growth of all but a few bacteria but at the same time facilitate isolation of certain bacteria
selective media
60
distinguish one microorganism from another growing on the same media by their growth characteristics
differential or indicator media
61
differential for lactose
and sucrose fermentation
Eosine methylene blue
62
differential for lactose fermentation
MacConkey
63
differential for mannitol fermentation
Mannitol salt agar (MSA)
64
differential for lac operon mutants for detection of recombinant strains of bacteria for study in molecular biology
X-gal plates
65
used to maintain the viability of certain delicate organisms in clinical specimens during their transport to the laboratory
transport media
66
transport media contains mainly?
buffers and salt
67
give example of transport media and its bacteria
Stuart’s transport medium for Neisseria gonorrhoeae
68
used for the short-term storage of bacterial
cultures
refrigeration
69
a process in which a pure culture of microbes is placed in a suspending liquid and quick-frozen at temperatures ranging from - 50º to -95°C
deep freezing
70
a suspension of microbes is quickly frozen at temperatures ranging from -54º to -95ºC, and the water is removed by a high vacuum (sublimation)
lyophilization (freeze drying)
71
common method of preserving strains of bacteria
cold storage
72
a process by which an article, surface, or medium is freed of all living microorganisms either in the vegetative or in the spore state
sterilization
73
any material that has been subjected to sterilization
sterile
74
a chemical agent that is used to perform sterilization because of their
ability to destroy spores
sterilants
75
also called a microbicide, is any chemical agent that kills pathogenic microorganisms either on inanimate (nonliving) materials or on living tissue but not resistant microbial cells
germicide
76
use of a chemical agent that destroys or removes all pathogenic organisms; used only on inanimate objects because they can be toxic to human and other animal tissue, when used in higher concentrations
disinfection
77
defined as the growth of microorganisms in the body or the presence of microbial toxins in blood and other tissues
sepsis
78
refers to any practice that prevents the entry of infectious agents into
sterile tissues and thus prevents infection
asepsis
79
chemical agents applied directly to the exposed body surfaces
(e.g., skin and mucous membranes), wounds, and surgical incisions to destroy or inhibit vegetative pathogens
antiseptics
80
any cleansing technique that mechanically removes
microorganisms (along with food debris) to reduce the level of contaminants
sanitization
81
a compound (e.g., soap or detergent) that is used to perform sanitization
sanitizer
82
reduces airborne microbes in hospital rooms, veterinary clinics, and laboratory installations
air sanitation with UV lamps
83
a process usually involves scrubbing the skin or immersing it in chemicals, or both
degerming/antisepsis
84
What are the methods of controlling microorganisms?
1. Sterilization
2. Disinfection
3. Antimicrobial
85
a natural method of sterilization of water in tanks, rivers, and lakes.
sunlight
86
one of the most dependable method of sterilization
heat
87
occurs in the form of hot water, boiling water, or steam (vaporized water) and the temperature usually ranges from 60 to 135°C
sterilization by moist heat
88
kills microorganisms by denaturation and coagulation of
proteins
moist heat
89
a technique in which heat is applied to liquids to kill potential agents of infection and spoilage, while at the same time retaining the liquid’s flavor and food value
pasteurization
90
product is exposed to heat at 72°C for 15–20 seconds followed by a
sudden cooling to 13°C or lower
flash method
91
product is
exposed to a temperature of 63°C for 30 minutes followed by cooling to
13°C or lower, but not less than 6°C
holder method
92
True or false.
Pasteurization inactivates most viruses and destroys the vegetative stages of 97–99% of bacteria and fungi, it does not kill endospores or thermoduric species (mostly nonpathogenic lactobacilli, micrococci, and yeasts)
True.
93
Two types of sterilization at a temperature of 100°C
Boiling and Steam sterilizer at 100°C
94
substances are exposed to steam at
atmospheric pressure for 90 minutes during which most vegetative
forms of the bacteria except for the thermophiles are killed by the moist
heat
Steam sterilizer at 100°C
95
carried out over a period of 3 days and requires a chamber to hold the materials and a reservoir for boiling water
tyndallization
96
the temperature is adequate to kill all the vegetative forms of the
bacteria, yeasts, and molds but not sufficient to kill spores.
1st day
97
surviving spores are allowed to germinate to vegetative forms and are killed on re-exposure to steam
2nd day
98
re-ensures killing of all the spores by their germination to vegetative forms
3rd day
99
makes use of air with a low moisture content that has been heated by a flame or electric heating coil
sterilization by dry heat
100
Sterilization of inoculating loop or wire, the tip of forceps, searing spatulas, etc., is carried out by holding them in the flame of the Bunsen burner till they become red hot.
flaming
101
an excellent method for safely destroying infective materials by burning them to ashes.
incineration
102
electrically heated and is fitted with a
fan to ensure adequate and even distribution of hot air in the chamber
hot air oven
103
remove contaminating microorganisms from solutions rather than directly destroying them
filtration
104
excellent sterilizing agent
with very high penetrating power. These radiations penetrate deep into objects and destroy bacterial endospores and vegetative cells, both prokaryotic and eukaryotic but not that effective against viruses
ionizing radiations
105
used for sterilization of antibiotics, hormones, sutures, catheters, animal feeds, metal foils, and plastic disposables, such as syringes, meat and other food items
gamma rays
106
Use of high-frequency sound (sonic) waves beyond the sensitivity
of the human ear are known to disrupt cells
sonication
107
transmits vibrations
through a water-filled chamber to induce pressure changes and create intense points of turbulence that can stress and burst cells in the vicinity
sonication
108
The process of inactivating microorganisms by direct exposure to chemical or physical agents
disinfection
109
are products or biocides that destroy or inhibit the growth of
microorganisms on inanimate objects or surfaces
disinfectants
110
are biocides or products that destroy
or inhibit the growth of microorganisms in or on living tissue
antiseptics
111
What are the properties of ideal disinfectant?
1. Wide spectrum of antimicrobial activity.
2. Act in the presence of organic matter.
3. Not toxic to human or corrosive.'
4. Stable during storage and not undergo any chemical change.
5. Odorless or with pleasant odor.
6. Soluble in water nd lipids for penetration into microorganisms.
7. Effective in acidic as well as alkaline in media.
8. Have speedy action.
9. If possible, should be relatively inexpensive.
112
What are the actions of disinfectants?
1. Produce damage to the cell wall and alter permeability of the cell membrane, resulting to exposure, damage, or loss of the cellular contents.
2. Alter proteins and form protein salts or cause coagulation of proteins.
3. Inhibit enzyme action and inhibit nucleic acid synthesis or alter nucleic acid molecules.
4. Cause oxidation or hydrolysis.
113
Factors Influencing Activity of Disinfectants
1. Temperature
2. Type of microorganisms
3. Physiological state of the cell
4. Environment
114
most widely used antiseptics and disinfectants in laboratories and hospitals worldwide
phenolic compounds
115
effective against
vegetative forms of bacteria but not suitable for application to skin or mucous
membrane
phenol
116
are more germicidal and less poisonous than phenol but corrosive to living tissues. They are used for cleaning floors (1% solution), for disinfection of surgical instruments, and for disinfection of contaminated objects
cresol
117
They are used as skin antiseptics and for
the cleaning of wound surfaces especially hexachlorophene because once applied it persists on the skin and reduces growth of skin bacteria for longer periods. However, it can cause brain damage and is now used in hospital
nurseries only after a staphylococcal outbreak
halogenated diphenyl compound
118
give disinfectants highly effective against both Gram- positive and Gram-negative bacteria
hexachlorophene and chlorhexidine
119
fluorine, bromine, chlorine, and iodine—a group of
nonmetallic elements that commonly occur in minerals, sea water, and salts
halogens
120
kills not only bacterial cells and endospores but also fungi and virus
chlorine
121
rapidly penetrates the cells of microorganisms, where it apparently disturbs a variety of metabolic functions by interfering with the hydrogen and disulfide bonds of proteins
iodine
122
most widely used disinfectants and antiseptics effective at a
concentration of 60–70% in water
alcohols
123
WHat are the most popular alcohol sporicidal and virucidal?
ethyl alcohol and isopropyl alcohol
124
are highly reactive molecules that combine with nucleic and
alkylating molecules; sporicidal and can be used as chemical sterilants
aldehydes
125
It is used to: preserve fresh tissue specimens, destroy anthrax spores
in hair and wool, prepare toxoids from toxins, sterilize bacterial vaccines, and kill
bacterial cultures and suspensions.
formaldehyde
126
used for sterilization of large volume of heat-sensitive disposable
items and also instruments
gases
127
ethylene oxide and betapropiolactone are examples of what disinfectants?
gases
128
alter energy relationship at interfaces producing a reduction in surface tension
surface active agents
129
organic molecules that serve as wetting agents and emulsifiers because they have both polar hydrophilic and nonpolar hydrophobic ends thus are very effective cleansing agents
detergents
130
This group includes halogens, hydrogen peroxide, potassium permanganate, and sodium perborate. They are good disinfectants
and antiseptics but are less effective in the presence of organic matter.
oxidizing agents
131
used extensively as skin and wound antiseptic
dyes
132
Soluble salts of mercury, silver, copper, arsenic, both have bactericidal and bacteriostatic. They combine with proteins, often with their sulfhydryl groups and inactivate
them or may also precipitate cell proteins
heavy metals
133
They kill microorganisms by
hydrolysis and altering the pH of the medium.
acids and alkaliss
