Test 3 Lecture 6 Flashcards
(141 cards)
1
Q
why do we want to control microorganisms in the environment?
A
to destroy pathogens and prevent their transmission.
to reduce or eliminate microorganisms responsible for the contamination of water, food, and other substances
2
Q
what is the destruction or removal of all viable organisms including endospores?
A
sterilization
3
Q
what are viable organisms?
A
organisms that can cause contamination or food spoilage
4
Q
what is a different type of sterilization that kills most bacteria and endospores, but still keeps the flavor of the food?
A
commercial sterilization
5
Q
what is the killing, inhibition, or removal of disease causing (pathogenic) organisms?
A
disinfection
6
Q
what are the chemical agents used for disinfection and what are they used on?
A
disinfectants and they are used on inanimate objects
7
Q
why are disinfectants not used on living tissues?
A
it can be harmful to the tissues
8
Q
what is the prevention of infection of living tissue by microorganisms?
A
antisepsis
9
Q
what are the chemical agents that kill or inhibit growth of microorganisms when applied to tissue?
A
antiseptics
10
Q
what do we use antiseptics on and why do we use them here?
A
they are used to wash our hands and living tissues bc they do not cause much harm or irritation to our skin
11
Q
what is the removing of microbes from a limited area?
A
degerming
12
Q
what is an example of degerming?
A
they do this on our skin before performing surgery bc our skin bacteria are pathogenic
13
Q
what is the reduction of microbial population to levels deemed safe (based on public health standards)? (this is not sterilization)
A
sanitization
14
Q
what is the use of chemicals to kill or inhibit growth of microorganisms within host tissue?
A
chemotherapy
15
Q
______ are non-specific and this is why they cannot be used to kill an infection inside the body. instead we take ______ for this because they are specific
A
antiseptics; antibiotics (which is part of chemotherapy)
16
Q
what are the chemotherapy agents that kill microorganisms and what are the agents that inhibit their growth?
A
kill = cidal agents
inhibit growth = static agents
17
Q
when you remove static agents, the bacteria will _____
A
begin to grow again
18
Q
for gram-negative infection we use _____ agents so that ______ are not released into our body
A
static agents; endo-toxins
19
Q
what suffix indicates that agent kills?
A
-cide
20
Q
what kills pathogens and many nonpathogenic but not necessarily endospores?
A
germicide
21
Q
what are the cidal agents?
A
bactericides, fungicides, algicides, and viricides
22
Q
what suffix indicates that agent inhibits growth?
A
-static
23
Q
what are the static agents?
A
bacteriostatic and fungistatic
24
Q
are bacteria killed instantaneously?
A
no, it takes time to kill bacteria
25
in bacteria the population death usually occurs _______
exponentially
26
what is a measure of an agent's killing efficiency?
decimal reduction time (DRT)
27
what is the time required to kill 90% of the bacterial population?
decimal reduction time (DRT)
28
you can compare 2 chemicals killing efficiency by their _____ value
DRT
29
which scale (log or arithmetic) have a linear relationship with the microbial death curve?
log scale (so we use the log scale)
30
the growth phase of the bacteria determine the effectiveness of an anit-microbial agent. bacteria that are in _____ phase are more susceptible than those in _____ phase.
log phase; stationary phase
31
____ and ____ protect the bacteria and do not let the anti-microbial agent get to them.
organic matter and biofilms
32
what are the actions of microbial control agents?
alteration of membrane permeability, damage to proteins, and damage to nucleic acids
33
what are the physical methods of control?
heat, low temperatures, high pressure, desiccation, osmotic pressure, radiation, filtration
34
what is the drying out and removing of water from an organism?
desiccation
35
what is the most common method for controlling microbial growth?
heat
36
what is the lowest temperature at which all cells in a culture are killed in 10 minutes?
thermal death point (TDP)
37
what is the minimum time required to kill all the bacteria in a liquid culture at a given temperature?
thermal death time (TDT)
38
what does moist heat destroy?
viruses, fungi, and bacteria
39
boiling will not destroy _____ and does not sterilize
spores
40
how does moist heat destroy microbes?
degrades nucleic acids, denatures proteins, and disrupts membranes
41
what sterilization method is steam under pressure?
autoclave
42
what is the temperature, pressure, and time used when autoclaving?
```
temp = 121 degrees celsius
pressure = 15 psi (1 atmosphere)
time = 20 minutes
```
43
the autoclave is effective against ______ microorganisms, including _____
all types of; spores
44
what type of material should not be placed inside the autoclave?
plastics
45
what is one of the most effective ways of killing endospores?
autoclave
46
how does the autoclave get to a temp of 121 degrees celsius?
it increases the pressure to 15 psi
47
in steam sterilization the steam must contact ______ to sterilize it.
the items surface
48
in steam sterilization _____ are placed with the item to tell you whether or not it is sterilized
indicator strips
49
what method reduces spoilage organisms and pathogens and is therefore not a sterilization method?
pasteurization
50
what are the equivalent treatments used in pasteurization?
63 degrees C for 30 min ; for high-temp short-time: 72 degrees C for 15 seconds ; ultra-high-temp: 140 degrees C for less than 1 second
51
what organisms survive pasteurization?
thermoduric organisms
52
what test has a protein enzyme that is sensitive to temperature and if it is still active then pasteurization is not complete? if it is not active then pasteurization is complete
phosphatase test
53
when the local drinking water is believed to be contaminated, area residents are advised to boil their water before drinking. often, however, they are not told how long to boil it. as a student of microbiology, what is your recommendation?
10 minutes
54
dry heat sterilization kills cells by _____ and it does what to proteins?
oxidation; it denatures proteins
55
what are the examples of dry heat sterilization?
flaming, incineration, hot-air sterilization
56
being in the autoclave for 15 min at 121 degrees C is equivalent to what in hot-air sterilization?
170 degrees C for 2 hours
57
what does low temp do to microbial growth?
it inhibits microbial growth, but does not kill them
58
what are examples of low temp microbial control?
refrigeration, deep-freezing, lyophilization
59
what is lyophilization?
desiccation or freeze drying (they have the water removed and are frozen)
60
where can fruits be stored after lyophilization?
they can be stored at room temp
61
what does high pressure do to microorganisms and which microorganisms does it affect?
it denatures proteins in microorganisms that are barosensitive
62
many of the spoilage bacteria are ______
barosensitive
63
does high pressure mess up the taste of fruit juices when sterilizing them?
no
64
how is osmotic pressure used to control microbial growth?
it uses a high salt concentration ( high osmotic pressure) to cause plasmolysis
65
what are the examples of ionizing radiation?
X rays, gamma rays, and electron beams
66
how does ionizing radiation work?
it ionizes water to release hydroxyl radicals. these hydroxyl radicals are toxic to the cells and damages their DNA
67
what is the wavelength and frequency of ionizing radiation waves?
they have low wavelength and high frequency which gives them high energy
68
is ionizing radiation effective against endospores?
yes
69
what is ionizing radiation used to sterilize and what can they not be used on.
they are used to sterilize sutures, plastic disposable supplies, and food; do not use them on liquids
70
what is non ionizing radiation and what is the wavelength?
UV, 260 nm
71
what can UV light kill and how does it do this?
it kills most bacteria and some endospores; it does this by causing DNA dimers (it damages DNA)
72
UV is limited to _____ bc it does not penetrate glass, dirt films, and water.
surface sterilization
73
in ______, water is being filtered to get rid of salts and the water is exposed to UV light to kill the bacteria
reverse osmosis drinking systems
74
what method kill bacteria by heat and is not especially antimicrobial?
microwaves
75
what are the radiation methods of control?
ionizing radiation, non ionizing radiation, and microwaves
76
which method is not a way to kill bacteria? it only separates bacteria from any liquid or air
filtration
77
______ reduces the microbial population or sterilizes solutions of heat-sensitive materials by removing microorganisms
filtration
78
______ allows the liquid to pass through but not the bacteria
membrane filters
79
porous membranes with defined pore sizes that remove microorganisms primarily by ______
physical screening
80
in filtration a _____ is used to create a positive pressure that pulls the liquid into the funnel
vacuum
81
porous membranes have replaced _______ for the most part
depth filters
82
do depth filters sterilize?
no, they will not remove bacteria that are present
83
_______ is also used to reduce microbial populations in the air
filtration
84
what are some examples of filtering air?
surgical masks, cotton plugs on culture vessels, high-efficiency particulate air (HEPA) filters
85
what is used in laminar flow biological safety cabinets to keep the air as sterile as possible?
high-efficiency particulate air (HEPA) filters
86
disinfectant must be effective against a wide variety of infectious agents at _____ concentrations
low
87
the ideal chemical must be effective in the presence of ______ and it should be ______ in storage
organic matter; stable
88
the ideal chemical should work in a wide range of ______ conditions
pH
89
the ideal chemical should take _____ time to kill bacteria
less
90
what test determines the lowest concentration of chemical that can kill bacteria for a given time?
use dilution test
91
in a use dilution test the rings with dried cultures are placed in the disinfectant for how long and at what temp?
10 minutes at 20 degrees C
92
in a use dilution test, after the bacteria are removed from the disinfectant, the rings are transferred to culture media to determine whether the bacteria ________
survived treatment
93
in a disk diffusion test what is the disk?
a piece of paper soaked in a known concentration of the chemical
94
in a disk diffusion test, what does the chemical from the piece of paper do?
the chemical will diffuse out into the agar and create a changing concentration
95
in a disk diffusion test what is the area around the disk called where there is no bacterial growth?
zone of inhibition
96
what are the 4 commonly used chemicals in a disk diffusion test?
chlorine, hexachlorophene, O-phenylphenol, quat
97
which chemicals are commonly used as laboratory and hospital disinfectants, they disrupt plasma membranes, and are long lasting
phenol and phenolics
98
what are the 2 bisphenols that are usually on cutting boards bc they are good at preventing microbial growth
hexachlorophene and triclosan
99
the bisphenols disrupt _____ and are present in _______
plasma membranes; hand sanitizers
100
hexachlorophene kills ______
staph aureus
101
what is used as a catalyst to create plastic and can be toxic?
bisphenol A (BPA)
102
what chemical is in cosmetics?
triclosan
103
what chemicals are safer than BPA and are not phenol derived?
biguanides
104
what is the example of a biguanide?
chlorhexidine
105
what chemical disrupts plasma membranes, is effective against gram positives and gram negatives, and is used on skin and mucous membranes (mouth wash)?
chlorhexidine (which is a biguanide)
106
what are the 2 halogens used in killing microorganisms?
chlorine and iodine
107
iodine causes _____ in aqueous alcohol, which are very irritating
tinctures
108
iodine forms ______ in organic molecules. this allows the slow release of iodine and it minimizes skin burns (less irritating)
iodophors
109
how does iodine kill microorganisms?
it alters protein synthesis and membranes
110
chlorine is very effective in cleaning ______
water
111
chlorine uses oxidizing agents and bleach is one form of chlorine that kills microorganisms. what chemical is present in bleach?
hypochlorous acid (HOCl)
112
chlorine destroys ______ and reacts with organic matter to form ______
vegetative bacteria and fungi (does not kill endospores); carcinogenic compounds
113
what compound is used to treat the carcinogenic compounds produced from chlorine reactions?
chloramine (chlorine + ammonia)
114
what are the alcohols that are used to kill microorganisms and how do they work?
ethanol and isopropanol; denature proteins and dissolve lipids
115
alcohols are very _____ and _____ at killing bacteria
fast and effective
116
______% alcohol is not effective at killing bacteria. why is this?
100; the proteins in the membrane denature very quickly and form a shell that protects the cell from letting the alcohol through
117
what is used to prevent the shell from completely forming, allowing the alcohol to get into the cell?
water
118
up to _____% of alcohol is still effective. less than this is not.
70%
119
how much of heavy metals are needed to kill bacteria?
very little quantities
120
what are the heavy metals used to kill bacteria?
Ag (silver), Hg (mercury), Cu (copper)
121
_____ may be used to prevent gonorrheal ophthalmia neonatorum (causes eye infection)
silver nitrate
122
_____ is used as a topical cream on burns to prevent growth of bacteria
silver sulfadiazine
123
_____ is an algicide (prevents growth of algae in a pond)
copper sulfate
124
_____ means that very few molecules are enough to kill bacteria
oligodynamic action
125
how do heavy metals work to kill bacteria?
they denature proteins. the + metals bond to the - proteins to form a complex and denature them
126
what are the surface active agents or surfactants?
soap, acid-anionic detergents, quarternary ammonium compounds (QUARTs)
127
what is the surfactant used in degerming? it reduces the surface tension of our skin oils to remove bacteria
soap
128
what is the surfactant used in public areas for sanitizing?
acid-anionic detergents
129
what is the surfactant that is bactericidal, denatures proteins, disrupts plasma membranes, are very effective, and are cationic detergents
quarternary ammonium compounds
130
what are the chemical food preservatives?
organic acids (weak acids) that slowly release ions to decrease the pH
131
what inhibits the metabolism of bacteria when the acid is produced?
organic acids
132
what are the organic acids that are used as chemical food preservatives?
sorbic acid, benzoic acid, and calcium propionate
133
what control molds and bacteria in foods and cosmetics?
organic acids
134
what chemical food preservative prevents endospore germination?
nitrite
135
antibiotics such as ______ and ______ prevent spoilage of cheese
nisin (bacteriocin); natamycin (anti-fungal)
136
what is a bacteriocin and what is an anti-fungal?
bacteriocin is produced by one bacteria to kill another type of bacteria. anti-fungal kills fungus
137
what inactivates proteins by cross-linking with functional groups? what are they functional groups that they bind to?
aldehydes; -NH2, -OH, -COOH, -SH
138
what are the aldehydes that are used to remove bacteria from medical equipment?
glutaraldehyde, formaldehyde, and ortho-phthalaldehyde
139
what is a gas and cross-links with proteins to denature them?
gaseous sterilants
140
what are gaseous sterilants used on?
heat-sensitive material
141
what are the gaseous sterilants?
ethylene oxide and chlorine dioxide (fumigation)
