3 - Sterilization and Disinfection Flashcards
1
Q
TOTAL inactivation of ALL forms of microbial life. Renders pathogen the inability to reproduce.
A
Sterilization
2
Q
Most resistant to sterilization
A
Spores
3
Q
Least resistant to sterilization
A
Viruses
4
Q
Destruction of microorganism capable of causing infection by means of a germicidal agent
A
Disinfection
5
Q
Reduction in the number of pathogens to a level that is unlikely to cause infection
A
Disinfection
6
Q
Disinfection is done on?
A
Inanimate objects and surfaces
7
Q
Are disinfectants sporicidal or sporostatic?
A
Sporostatic
8
Q
A germicidal agent that destroys or kills bacteria by an irreversible process.
A
Bactericidal
9
Q
A germicidal agent that reversibly inhibits the growth of bacteria.
A
Bacteriostatic
10
Q
TOPICAL chemical agent applied to a body surface or living tissue that kills or inhibits the growth of pathogenic microorganisms
A
Antiseptic
11
Q
Use of disinfectant to lower microbial content of inanimate objects/utensils
A
Sanitization
12
Q
Antiseptic is applied to?
A
Body surfaces
13
Q
Compare antiseptic and disinfectant: action
A
Antiseptic: Bacteriostatic
Disinfectant: Bacteriocidal
14
Q
Regarded as drug
A
Antiseptic
15
Q
Regarded as environmental poison
A
Disinfectant
16
Q
Used at the lowest concentration that results to desired effect
A
Antiseptic
17
Q
Used at highest concentration
A
Disinfectant
18
Q
Lowers microbial counts on eating and drinking utensils to safe public health levels
A
Sanitization
19
Q
Prevention of multiplication of microorganisms in formulated objects (pharmaceuticals and foods
A
Preservation
20
Q
Two methods of sterilization
A
Physical and Chemical
21
Q
Most reliable; universally applicable; simplest method of sterilization
A
Heating
22
Q
6 mechanisms of thermal injury caused by heating.
A
- Single strand breaks
- Membrane integrity
- Protein denaturation/coagulation
- Oxidative damage
- Elevated electrolytes
- Simulated environment for growth
23
Q
The sterilization of a bacterial population by heat is a GRADUAL process. True or False?
A
True
24
Q
How is the kinetics of death of pathogens described in heating?
A
Exponential
25
Preferred method of heating
Use of MOIST heat
26
Vegetative forms are destroyed in moist heat at ____ in ____ minutes
80C in 5-10 minutes
27
Spores are destroyed in moist heat at ____ in ____ minutes
120C in 4 minutes
| 100C in 5.5 hours
28
True or false. LOWER temperature = shorter time to kill.
False. Higher temperature = shorter time to kill
29
Moist heat basically kills microorganisms by ______.
Protein denaturation
30
4 forms of Moist Heat sterilization
1. Steam under pressure (autoclaving)
2. Boiling
3. Fractional sterilization/Tyndallization
4. Pasteurization
31
Used for sterilizing materials that would be damaged by autoclaving
Fractional sterilization/Tyndallization
32
Kills ALL VEGETATIVE forms of pathogenic organisms at 80-100 °C for 10-30 minutes but NOT bacterial ENDOSPORES
Boiling
33
Boiling kills all vegetative forms of pathogens at ____ C for ___ minutes.
80-100C for 10-30 minutes
34
Heating 80-100 °C x 30 minutes for 3 consecutive days with incubation periods in between
Fractional sterilization/Tyndallization
35
Most efficient method of moist heat sterilization
Steam under pressure (autoclaving)
36
Allows application of moist heat above the normal atmospheric boiling point of water
Steam under pressure (autoclaving)
37
Temp. at which autoclaving is done at 15 psi for 15-90 minutes
121C
38
Temp. at which autoclaving is done at 27 psi for 4-20 minutes
132C
39
Used to sterilize surgical bandages, instruments, media
| and to decontaminate reusable supplies and equipment
Steam under pressure (autoclaving)
40
One disadvantage of steam under pressure
Damages heat-sensitive materials
41
This method of moist heat sterilizations is cumbersome/impractical for everyday use.
Boiling
42
One advantage of boiling
Minimal equipment is used
43
Used to sterilize HEAT-SENSITIVE MATERIALS, BACTERIOLOGIC MEDIA, SOLUTIONS OF CHEMICAL
Fractional sterilization or Tyndallization
44
Temp of pasteurization
Below boiling point (77C)
45
Used to sterilize milk and dairy products, food and beverages
Pasteurization
46
True or False. Relatively heat-resistant bacteria survive pastuerization but are unlikely to cause disease.
True
47
True or False. Pasteurization can be ised on heat sensitive liquids and medical devices.
True.
48
An unreliable sporicidal in moist heat sterilization
Pasteurization
49
This method of heat sterilization requires higher temperature and longer exposure to heat
Dry heat
50
Where does DRY HEATING depend upon to be effective?
Effectiveness of dry heat depends on penetration of heat through the material
51
How does DRY HEAT kill all microrganisms?
Through its OXIDATION effects
52
3 forms of Dry Heat Sterilization
Hot air oven
Red heat flame
Incineration
53
Most widely used Dry Heat method
Hot air oven
54
Temp of dry heat
160-180C for 2-4 hrs
55
Dry Heat method ised for anhydrous materials, oils and powder, lab glassware and instruments
Hot air oven
56
Sterilization via oxidation to ashes/burning
Red heat flame
57
Used in sterilization of inoculating loops, needles
Red Heat Flame
58
Sterilization via oxidation to ashes/burning at temp >1000C
Incineration
59
Sterilization technique in decontamination of waste items prior to disposal (hospital wastes)
Incineration
60
Penetrates water insoluble materials
Hot air oven
61
Disadvantages include slow diffusion and not suitable to reusable plastics
Hot air oven
62
Less corrosive to metals and sharp instruments
Hot air oven
63
Rapid heating method
Red heat flame
64
Initial contact with flame produces a viable aerosol
Red heat flame
65
May lead to accidental fire
Red heat flame
66
Reduces volume of waste by 95%
Incineration
67
One disadvantage is this requires transport of infectious waste
Incineration
68
Aside from pasteurization, this sterilization technique is not reliably sporicidal and is time consuming too
Fractional sterilization/tyndallization
69
One disdavantage is shielding dirt must first be removed
Autoclave
70
Most dependable heat sterilization technique
Autoclave
71
Another physical method of sterilization in which it deprives bacteria of water, thus inhibiting its growth and reproduction
Dessication
72
Resistant to drying or dessication
Bacterial spores
73
Used in preservation of foods
Dessication
74
Inhibiting bacterial metabolism and growth by exposing it to very low temperatures
Freezing
75
True or False. Freezing destroys microorganisms
False
76
In which bacteria is freezing ineffective
Psychrophiles/cryophiles
77
When is freezing used?
Preservation of foods
78
Similar to freezing but is done rapidly. Samples are stored in sealed ampules. Has longer shelf life.
Lyophilization
79
Used in: laboratories, pharmaceuticals,cryogenic
Lyophilization
80
2 forms of radiation
UVL
| Ionizing Radiation
81
Most effective bactericidal
Ultraviolet Light
82
Wave length of UVL and optimum emitted by UV lamps
240-280nm; optimum 260nm
83
Germicidal and reduces the number of microbes on exposed surfaces and in air
UVL
84
Used normally in disinfecting air
UVL
85
3 disadvantages of UVL
Poor penetrating power
Hazardous to skin and eyes
Damages DNA
86
Has greater penetrating ability than UVL because it has shorter wavelength and carries MORE energy.
Ionizing Radiation
87
One disadvantage of ionizing radiation
Potentially hazardous to human cells
88
Mechanical sieving or physical separation of microorganism from the fluid
Filtration
89
What is used in filtration
Cellulose ester membranes
90
Size that allows passage through filtration
0.22 um
91
Physical sterilization that makes use of salt addition
Osmotic pressure
92
Method for vaccine preparation
Lyophilization
93
Examples of organisms that can pass through filter paper
Viruses, chlamydia, rickettsia, mycoplasma
94
Produces ions and other reactive molecular species from molecules with which the radiation particles collide
Ionizing Radiation
95
Give example of sterilization by osmotic pressure
Used in dried fish
96
Disrupts cells via bacterial cavitation causing disintegration and denaturation
Use of ultrasonic vibrations
97
Formation of partial vacuum in a liquid medium
Bacterial cavitation
98
Used for breaking open tissue cells and treating renal or gall stones
Ultrasonic vibration
99
5 modes of actions of sterilants or disinfectants
1. Damage to DNA
2. Protein denaturation
3. Cell membrane or wall disruption
4. Removal of free sulfhydryl groups
5. Chemical antagonism
100
3 chemicals that damage the cell membrane
1. Surface active disinfectants
2. Phenolic compounds
3. Alcohol
101
Alters the energy relationships at interfaces causing reduction of surface tension
Surface Active Disinfectants or Surfactants
102
How does a surface active disinfectant denature microbial enzymes and proteins?
By disrupting the hydrogen and sulfide bonds causing a block in metabolism
103
Distorts cellular membrane and loss of membrane permeability causing leakage of N and P containing compounds
Cationic Compounds - Quaternary ammonium compounds
104
Surface Active Disinfectant most effective at alkaline pH
Cationic Compounds - Quaternary ammonium compounds
105
Are Cationic Compounds - Quaternary ammonium compounds sporicidal or sporostatic?
Sporostatic - inhibits the growth but not the actual germination process
106
Mycobacteristatic
Cationic Compounds - Quaternary ammonium compounds
107
Have an effect on enveloped but NOT LIPID-enveloped viruses
Cationic Compounds - Quaternary ammonium compounds
108
Examples of Cationic Compounds - Quaternary ammonium compounds
Zephiran
| Benzalkonium chloride
109
Disrupts lipoprotein framework of the CM and most effective at acid pH
Anionic compunds - Soaps and detergents
110
Causes leakage of cell contents and IRREVERSIBLE INACTIVATION of membrane bound oxidases and dehydrogenases
Phenolic Compounds
111
Kill bacteria, most fungi & some viruses but are ineffective against endospores
Phenolic Compounds
112
Rapid, broad-spectrum antimicrobial activity against vegetative bacteria, viruses, and fungi but are not sporicidal
Alcohols
113
Activity is optimal when they are diluted to a concentration of 60-90% with water
Alcohols
114
Most effective alcohol at 50 - 70% and is used as a skin disinfectant
Ethyl aclohol
115
Alcohol that cannot destroy spores at normal temp
Ethyl acohol
116
Less volatile alcohol, has greater bactericidal activity and toxic effect
Isopropyl alcohol
117
2 chemicals for protein denaturation
1. Acids and Alkalis
| 2. Alcohol and acetone
118
Exert their action through free H and OH ions and alter the pH of the organism’s environment
Acids and alkalis
119
4 chemicals for for functional group, proteins and Nucleic Acid Modification
1. Heavy metals
2. Oxidizing agents
3. Dyes
4. Alkylating agents
120
How do heavy metals poison enzyme activity?
By forming mercaptides with the SH groups of cysteine residues
121
Not reliable heavy metal disinfectants
Mercurials: merthiolate and mercurochrome antiseptics
122
Prevents gonococcal ophthalmia
Silver nitrate 1%
123
Used to combat fungal diseases of plants and is also a common algicide
Copper sulfate
124
Inactivate enzymes converting functional SH groups to oxidized S-S for stronger agents; also attack amino groups, indole groups and phenolic hydroxyl groups of tyrosine
Oxidizing agents
125
Oxidizing agent that is bactericidal; effective against sporulating org, Mycobacterium tuberculosis
Halogens
126
Oxidizing agents that destroy the cellular activity of proteins; examples are chlorine and iodine
Halogens
127
BEST antiseptic because it kills spores, viruses, fungi, some endospores; usually dissolved in an alcohol solution to produce a tincture
Iodine
128
Combination of iodine and an anionic detergent that reduces surface tension and slowly releases the iodine
Iodophores
129
Complexes of iodine and a solubilizing agent or carrier
Iodophores
130
Example is povidone-iodine
Iodophore
131
Liberates free chlorine and is used as WATER DISINFECTANT
Chlorine
132
Sanitizes dairy and food processing equipment household and hospitals
Hypochlorite
133
Active agent in household bleach
Sodium hypochlorite
134
Weak antiseptic; has broad spectrum of activity however, it should be applied in higher concentrations of about 10-30% which is already very toxic to humans
Hydrogen peroxide
135
Once used in cleaning wounds, disinfection of surgical devices and soft plastic contact lenses
Hydrogen peroxide (H2O2)
136
Limited in treatment of dermatologic lesions; stain bacteria
Dyes
137
o Brilliant green
o Malachite green
o Crystal violet
Triphenylmethane
138
o Wound antiseptics
| o Retain antimicrobial activity in the presence of serum
Acridines
139
An alkylating agent that preserves specimens and used in preparation of vaccine ( whole-killed and toxoid)
Formaldehyde (formalin)
140
Kill M. tuberculosis in sputum and fungus in athlete’s foot; destroys all org including spores
Formaldehyde (formalin)
141
Sporicidal, virucidal and bactericidal; 10x more effective than formaldehyde and less toxic
Glutaraldehyde
142
Cold sterilant for surgical instruments e.g. Cidex
Glutaraldehyde
143
Gas sterilization of 50-1200 mg/L x 1-12 hrs
Ethylene oxide
144
Penetrates packaging material (polyethylenes tubes, electronic and medical equipment, biological and drugs)
Ethylene oxide
145
Sterilizes heart and lung machines
Ethylene oxide
146
potentially mutagenic and carcinogenic in humans (vapors are toxic to skin, eyes and mucous membranes)
Ethylene oxide
147
6 factors affecting disinfectant potency
1. Concentration of chemical agent
2. Time
3. Temperature
4. pH
5. Nature of medium
6. Nature of agent
148
Higher concentration of chemical agent means the disinfectants is bacteriocidal or bacteriostatic?
Bacteriocidal
149
True or False Increase in time of contact = increase killing of morgs
True
150
Effect of excessive heat
Protein denaturation
151
True or False.The H+ ion conc. influences both the organism and chemical agent
True
152
Determines the degree of ionization of the chemical agent
pH
153
presence of extraneous materials increases the efficiency of chemical agent. true or false.
False. Increases
154
Standard reference material based on tube dilution procedure determine the ratio of the highest dilution that will kill the org within a specified time to the greatest dilution of phenol showing the same result
Phenol coefficient test
155
2 organisms used in the phenol coefficient test
1. Salmonella typhi
| 2. Staphylococcus aureus
156
Another method of evaluating chemical disinfectant efficacy that utilizes an agar and a paper
Filter Paper method
157
Most efficacious disinfectant that completely kills microbes at lowest dilutions
Use-dilution test
158
Organism air dried onto a stainless steel surface >> exposed to disinfectant : following sterile water rinsing the entire surface placed in broth >> successful disinfection >> no bacterial growth in the broth
Use-dilution test
