CHAPTER 6 Flashcards
1
Q
Antimicrobial agent
A
Anything that kills (cidal) or inhibits the growth of (static) microbes
2
Q
Aseptic
A
Environment that is free of contamination
3
Q
Sterilization
A
destruction of all microorganisms and viruses in or on an object
4
Q
Sterile
A
any object that has been subjected to sterilization.
5
Q
Disinfection
A
Involves the use of physical or chemical agents known as disinfectants, that inhibit or destroy vegetative microbes (not endospores) and many viruses on inanimate objects
6
Q
Disinfectant
A
Involves the use of physical or chemical agents known as disinfectants, that inhibit or destroy vegetative microbes (not endospores) and many viruses on inanimate objects
7
Q
Antisepsis
A
Reduction in the number of microorganisms and viruses, particularly potential pathogens on living tissues.
8
Q
Antiseptic
A
inhibit or destroy vegetative microbes (not endospores) and many viruses on living tissue
9
Q
degerming
A
Removal of microbes by mechanical means
10
Q
sanitization
A
Removal of pathogens from objects to meet public health standards
11
Q
pasteurization
A
use of heat to destroy pathogens and reduce the number of spoilage microorganisms in foods and beverages
12
Q
-static and -cidal
A
static- inhibition
cidal- destroy kill
13
Q
Microbial death
A
The permanent loss of reproducibility under ideal environmental conditions.
14
Q
Microbial death rate
A
The number of bacteria that die over a given period.
15
Q
Germicide Classification
A
Relative susceptibility of microorganisms
16
Q
High Level
A
Kill all pathogens, including endospores
17
Q
Intermediate Level
A
kill fungal spores, protozoan cyst, viruses, and pathogenic bacteria
18
Q
Low Level
A
Kill vegetative bacteria, fungi, protozoa, and some viruses
19
Q
Biosafety level
A
Four levels of safety in labs dealing with pathogens
• Biosafety Level 1 (BSL-1) Handling pathogens that do not cause disease in healthy humans
• Biosafety Level 2 (BSL-2) Handling moderately hazardous agents
• Biosafety Level 3 (BSL-3) Handling microbes in safety cabinets
• Biosafety Level 4 (BSL-4) Handling microbes that cause severe or fatal disease
20
Q
Heat-Related Methods
A
Effects of high temperatures:
Denature proteins
Interfere with the integrity of the cytoplasmic membrane and cell wall
Disrupt structure and function of nucleic acids
21
Q
thermal death point
A
The lowest temperature that kills all cells in broth in 10 minutes
22
Q
thermal death time
A
Time to sterilize volume of liquid at set temperature
23
Q
decimal reduction time (D)
A
The number of minutes it takes for a defined temperature to reduce the number of viable bacteria in a sample by 90%
24
Q
Moist heat
A
Used to disinfect, sanitize, sterilize, and pasteurize
Denatures proteins and destroys cytoplasmic membranes
More effective than dry heat
25
Methods of microbial control using moist heat:
Boiling
Autoclaving
Pasteurization
Ultra-high temperature sterilization
26
Boiling
Kills vegetative cells of bacteria and fungi, protozoan trophozoites, and most viruses
• Boiling time is critical
• Different elevations require different boiling times
• Endospores, protozoan cysts, and some viruses can survive
boiling
27
Autoclave
Pressure applied to boiling water prevents steam from escaping
• Boiling temperature increases as pressure increases
• Autoclave conditions: 121°C, 15 psi, 15 minutes
28
Pasteurization
Used for milk, ice cream, yogurt, and fruit juices • Not sterilization
• Heat-tolerant and heat-loving microbes survive
29
ultra-high-temperature sterilization
140°C for 1 to 3 seconds, then rapid cooling
• Treated liquids can be stored at room temperature
30
Dry heat
Used for materials that cannot be sterilized with moist heat
Denatures proteins and oxidizes metabolic and structural chemicals
Requires higher temperatures for longer time than moist heat
Incineration is ultimate means of sterilization
31
Desiccation
Desiccation (drying) inhibits growth due to the removal of water
32
Lyophilization
(freeze-drying) is used for the long-term preservation of microbial cultures. Prevents the formation of damaging ice crystals
33
Filtration
Fluids are forced through a filter that traps any microbes that may be present
Commonly used for media that cannot be autoclave sterilized
Filter size dictates what is allowed through
34
Bio safety cabinet
type of biocontainment equipment used in biological laboratories to provide personnel, environmental, and product protection.
35
Osmotic pressure
High concentrations of salt or sugar in foods to inhibit growth
Cells in hypertonic solution of salt or sugar lose water
Fungi have greater ability than bacteria to survive hypertonic environments
36
Ionizing radiation
Wavelengths shorter than 1 nm (examples: electron
beams, gamma rays, some X rays) can cause molecules to ionize
What are ions and what effect might they have on microbes?
Electron beams effective at killing microbes but do not penetrate well
Gamma rays penetrate well but require hours to kill microbes, X rays require long time to kill microbes
Not practical for microbial control
37
non-ionizing radiation
Wavelengths greater than 1 nm (example: UV light) excites electrons, but does not form ions
▪ Affects 3-D structure of proteins and nucleic acids
▪ UV light causes pyrimidine dimers in DNA
▪ UV light does not penetrate well
▪ Suitable for disinfecting air, transparent fluids, and surfaces of objects
38
Phenols and phenolics
Denature proteins and disrupt cell membranes Effective in presence of organic matter
Remain active for prolonged time
Commonly used in health care settings and labs Have disagreeable odor and possible side effects
39
Alcohols
Intermediate-level disinfectants
Denature proteins and disrupt cytoplasmic membranes
More effective than soap in removing bacteria from hands
Swabbing of skin with alcohol prior to injection removes most microbes Not effective against fungal spores or bacterial endospores
Examples: ethanol, isopropanol, methanol
40
Halogens
Intermediate-level antimicrobial chemicals Damage enzymes by denaturation
▪ Chlorine ▪ Iodine
41
Oxidizing agents
High-level disinfectants and antiseptics Peroxides, ozone, and peracetic acid
Kill by oxidation of microbial enzymes
Hydrogen peroxide can disinfect and sterilize surfaces
Not useful for treating open wounds due to catalase activity Ozone treatment of drinking water and air
Peracetic acid is an effective sporicide used to sterilize equipment
▪ Hydrogen peroxide ▪ Ozone (O3)
42
Surfactants
Surface active” chemicals. Reduce surface tension of solvents
Soaps - have hydrophilic and hydrophobic ends
• Good degerming agents but not antimicrobial
Detergents- Detergents are positively charged organic surfactants
43
Heavy metals
Low-level bacteriostatic and fungistatic agents Heavy-metal ions denature proteins
1% silver nitrate once used to prevent blindness caused by Neisseria gonorrhoeae
Thimerosal used to preserve vaccines
Silver, zinc, mercury, lead, arsenic, etc.
44
Aldehydes
cross-link functional groups to denature proteins and inactivate nucleic acids
Formaldehyde - Formalin is used in embalming and disinfection of rooms and instruments
Glutaraldehyde- Glutaraldehyde disinfects and sterilizes
45
Enzymes
Antimicrobial enzymes act against microorganisms Human tears, saliva, and breast milk contain lysozyme Digests peptidoglycan cell wall of bacteria
▪ Lysozymes- Digests peptidoglycan cell wall of bacteria
▪ Prionzymes- Prionzyme can remove prions on medical instruments
46
Antimicrobial drugs
Antibiotics, semisynthetic, and synthetic chemicals
Typically used for the treatment of disease
Some used for antimicrobial control outside the body
47
Anything that kills (-cidal) or inhibits the growth of (-static) microbes is an?
Antimicrobial
48
What are the three classes of antimicrobial agents?
1.Physical agents
2. Chemical agents
3. Chemotherapeutic
49
An environment that is free of contamination is called?
Aseptic
50
Procedures taken to maintain an environment that is free of contamination are called?
Sterilization
51
What are the three main methods of achieving aseptic conditions?
1. Sterilization
2.disinfection
3. antisepsis
52
Which of the three methods of achieving aseptic conditions involves the use of chemical or physical methods to inhibit or destroy vegetative microbes and viruses, but not endospores from inanimate objects?
Disinfectant
53
Which of the three methods of achieving aseptic conditions involves the use of chemical or physical methods to inhibit or destroy vegetative microbes and viruses, but not endospores from living tissues?
Antisepsis
54
Which of the three methods of achieving aseptic conditions involves the use of chemical or physical methods to remove all microbes, including endospores from an object?
Sterilization
55
Heating food products enough to reduce the number of vegetative microbes that could potentially spoil the food item is an example of?
Pasteurization
56
Spraying and wiping down a lab bench with a chemical disinfectant is an example of?
Degerming
57
A worker at a restaurant running used dishes and eating utensils through a high- heat dishwasher is an example of?
Sanitization
58
What is the difference between the suffixes -static and -cidal?
a. Know the difference between each:
i. Bactericidal agent vs. Bacteriostatic agent
ii. Fungicidal agent vs. Fungistatic agent
iii. Protozoacidal agent vs. Protozoastatic agent iv. Virucidal agent vs. virustatic agent
v. Sporicidal agent vs. Sporistatic agent
59
What does microbial death mean?
The permanent loss of reproductive ability under ideal environment conditions
60
What does microbial death rate mean and why is determining microbial death rates important?
The number of bacteria that die over a given period
61
Be able to determine the microbial death rate if given the appropriate data.
Example:
A broth tube contains 1,000,000,000 cells (109 or 1 billion) and a chemical antimicrobial agent is added to the tube which results in a 10% decrease in the number of cells after exactly one minute.
What is the microbial death rate for this sample?
What percentage of the cells would die off after each additional minute of exposure to the antimicrobial agent?
1 minute
90%
62
What are those two main targets (aka mechanisms of action) of antimicrobial agents?
Alteration of cell walls and membranes -bacterial cell walls can rupture Damage to proteins and nucleic acids-damage DNA or destroy -die
63
What are four characteristics of a good antimicrobial agent?
Inexpensive
Fast-acting
Stable-during storage
Capable of controlling microbial growth while being harmless to humans, animals, and objects.
64
What are three factors that can affect the efficiency of antimicrobial agents?
Site to be treated
Relative susceptibility of microorganisms Environmental conditions
65
Why is the site to be treated important to know?
Method of microbial control based on site of medical procedures.
66
What are the three most resistant microbes to physical and chemical antimicrobials?
Prions
Endospores
Cyst of cryptosporidium
67
What are the three most resistant microbes to physical and chemical antimicrobials?
Endospores
68
What are the three levels of germicide classification? Which of those can lead to sterilization?
High level- Kill pathogens and endospores.
Intermediate- Fungal spores, protozoan cyst
Low-level -germicide
69
An antimicrobial agent must be able to destroy what type of microbes before it can be considered a sterilant?
Pathogens and endospores
70
What are the two main environmental factors and why are each significant when determining the most effective antimicrobial agent to use?
Temperature and PH
Organic material
71
Do high temperatures and acidic pH typically increase or decrease the efficacy of antimicrobial agents?
Decreases
72
What are the four biosafety levels and which level contains the most dangerous microbes and which contains the least dangerous microbes?
a. Biosafety Level 1 (BSL-1) Handling pathogens that do not cause disease in healthy humans
b. Biosafety Level 2 (BSL-2) Handling moderately hazardous agents
c. Biosafety Level 3 (BSL-3) Handling microbes in safety cabinets
d. Biosafety Level 4 (BSL-4) Handling microbes that cause severe or fatal disease
73
What are the two methods of microbial control covered in this chapter?
Physical and chemical
74
Selective toxicity is the ability of an antimicrobial agent to damage or destroy the microbes while being a harmless as possible to human cells. Do the two methods of microbial control covered in this chapter exhibit high or low selective toxicity?
NO
75
What are the six classes of physical control methods we covered in class?
i. Heat-Related Methods
ii. Refrigeration and Freezing
iii. Desiccation and Lyophilization iv. Filtration
v. Osmotic Pressure
vi. Radiation
76
What effect does temperature have on the efficacy of antimicrobial chemical agents?
Increases the efficacy
77
How does heat typically destroy microorganisms? Is heat typically static, cidal, or potentially both?
Denatures proteins, Interfere with cytoplasm membrane and cell wall.
Both Cidal and static depending on the temperature.
78
Thermal death point
determine their values if given an example: It took 65C to kill all the bacteria of a bacterial species in exactly 10 minutes. What is the thermal death point for this sample?
The lowest temperature that kills all cells in broth in 10 minutes
65C
79
Thermal death time
determine their values if given an example:
1. It took 10 minutes to kill all the bacteria in a broth sample when exposed to 65C. What is the thermal death time for this sample?
2. It took 23 minutes to kill all the bacteria in a broth culture when exposed to 87C. What is the thermal death time for this sample?
1.10 min
2. 23 min
80
Decimal deduction time
determine their values if given an example: It took 11 minutes to kill 90% of the bacteria in a broth culture. What is the decimal reduction rate for this sample? 11min
The number of minutes it takes for a defined temperature to reduce the number of viable bacteria in a sample by 90%.
11 minutes
81
What effect would a decrease or increase in the susceptibility level of organisms have on the thermal death point and thermal death time?
Example: Which would have a higher thermal death point?
1. A 1ml broth culture of mycobacterium (an acid-fast bacterial species) or a 1 ml broth culture of E.coli (a gram-negative bacterial species)?
Example: Which would have a higher thermal death time?
2. A 1ml broth culture of mycobacterium (an acid-fast bacterial species) or a 1 ml broth culture of E.coli (a gram-negative bacterial species)?
1. A 1ml broth culture of mycobacterium (an acid-fast bacterial species)
2. A 1ml broth culture of mycobacterium (an acid-fast bacterial species)
82
What effect would an increase in volume have on the thermal death point and thermal death time?
Example: Which would have the lowest thermal death point and lowest thermal death time and which would have the highest thermal death point and thermal death time?
1. 8ml broth culture of mycobacterium 2. 4ml broth culture of Mycobacterium 3. 1 ml broth culture of Mycobacterium
1 ml broth culture of Mycobacterium
83
Does the volume of a broth culture affect the decimal reduction time (D)?
Yes
84
What are the two forms of heat-related methods?
Moist heat-most effective
Dry heat-dissipates
85
What are the four forms of moist heat?
Boiling
Autoclaving
Pasteurization
Ultra high temperature sterilization
86
Which of the four methods of moist heat can lead to sterilization?
Autoclaving
87
Exposing a liquid to 140C for a few seconds followed by rapid cooling is an example of?
Ultra-high heat
88
Boiling will kill vegetative cells and most viruses but commonly will not kill what type of microbes?
Endospores
89
Placing an object in a pressured chamber that allows for the temperature to reach 121C and will lead to sterilization usually after 15 minutes is called?
Autoclaving
90
Heating food items just enough to kill most vegetative microbes that may cause spoilage is an example of which form of moist heat?
Pasteurization
91
What are two examples of dry heat methods, and which is considered the ultimate source of sterilization?
1. Hot Air
2. Incineration
92
Refrigeration typically involves temperatures of what range?
0-7C
93
Freezing involves temperatures below?
Below 0C
94
Is refrigeration typically static, cidal, or potentially both?
Static
95
Is freezing static, cidal, or potentially both?
Static
96
How does refrigeration and freezing work to inhibit the growth of microbes?
Decreases microbial metabolism and growth reproduction.
97
Does refrigeration inhibit all microbes? If not, what type of organisms does refrigeration not inhibit?
NO
98
The dehydration of microbes using heat to inhibit or destroy microbes is called?
Desiccation
99
The freeze drying of microbes with hopes to preserve them for later use is called?
Lyophilization
100
Fluids (e.g., broth media) being forced through a membrane that contains small pores that allow the smaller fluid molecules to travel through but prevents the larger microbes from passing through into a sterile container is called?
Filtration
101
Is filtration static, cidal, or neither?
Neither
102
To sterilize a broth culture, the pore size of the filter has to be (smaller or larger) than the size of the smaller microbe in the medium?
Smaller
103
A hood that circulates filtered air to create an aseptic environment is called?
Biosafety cabinet
104
The use of solutes to create a hypertonic environment that dehydrates cells to inhibit and sometimes kills the cells is called?
Osmotic pressure
105
What are two common solutes that are used to create hypertonic environments?
1.Salt
2. sugar
106
What determines whether the osmotic pressure method is static or cidal?
The concentration of salt and sugar
107
Energy waves of electromagnetic energy that can be used to damage or destroy microbes is called?
Radiation
108
Ionizing radiation includes wavelengths that are (shorter or longer) than the UV range?
Shorter
109
Non-ionizing radiation includes wavelengths that are in the UV range or wavelengths that are (shorter or longer) than the UV range?
Longer
110
Which type of radiation is the main form of non-ionizing radiation used to control microbes and how does this form of radiation affect microbes?
UV light breaks down the proteins and nucleic acids.
111
Is ionizing or non-ionizing radiation more effective as an antimicrobial?
Ionizing
112
The act of physically scrubbing or wiping down a surface, usually couple with a chemical agent is called?
Give a couple examples of this:
Degerming
Wiping the table down
113
Chemical control agents work by damaging or destroying cell membranes, cell walls, denaturing proteins (such as enzymes), and DNA. Which of those is the most common mechanism of action by chemical antimicrobial agents?
Phenols and phenolics
114
What are the nine classes of chemical antimicrobial control agents?
1. Phenol and Phenolics
2. Alcohols
3. Halogens
4. Oxidizing agents
5. Surfactants
6. Heavy metals
7. Aldehydes
8. Enzymes
9. Antimicrobial drugs
115
Phenols and Phenolics
a. What is the germicide classification?
b. Phenols and phenolics function by?
c. Why are phenols and phenolics are effective when treating surfaces or objects that are contaminated with organic matter?
Intermediate level
Denaturing proteins
Because they do a good job of penetrating through substances.
116
Alcohols
a. What is the germicide classification?
b. Alcohols function by?
c. What are the most commonly used alcohols?
d. Alcohols can be used as a disinfectant, antiseptic, or both?
Intermediate level
Denature proteins and disrupt cytoplasm membrane
Ethanol and isopropanol
Both
117
Halogens
a. What is the germicide classification?
b. Halogens function by?
c. What are the two main examples of halogens and what each are commonly used for?
Intermediate level
Damage enzymes by denaturation
Iodine Tablets and Chlorine treatments.
118
Oxidizers
1.What is the germicide classification?
2. Oxidizing agents function by?
3. What are the three types of oxidizing agents and what each are commonly used for?
4. Hydrogen peroxide is a good skin antiseptic but why doesn’t it work well for open skin wounds?
1. High level -cidal
2. Oxidization of microbial enzymes
3a. Peroxides, ozone, and peracetic acid
3b. Kill by oxidation of microbial enzymes
3c. Hydrogen peroxide can disinfect and sterilize surfaces
4. Not useful for treating open wounds due to catalase activity
119
Surfactants
a. What is the germicide classification?
b. What are the two types of surfactants and how does each work?
c. Which of the two types of surfactants is cidal and which is neither cidal nor static?
Low level
a. “Surface active” chemicals Reduce surface tension of solvents
b. Soaps and detergents Soaps have hydrophilic and hydrophobic ends, Good degerming agents but not antimicrobial. Detergents are positively charged organic surfactants
Surfactant active – cidal Soap and detergent – neither
120
Heavy Metals
a. What is the germicide classification?
b. Heavy metals (including silver, copper, mercury, zinc, etc.) functions by?
c. Heavy metals have a static effect against which two of microbes?
Low level
Denature protein and enzymes
Bacteria and fungi
121
Aldehydes
a. What is the germicide classification?
b. Aldehydes function by?
c. What are the two examples of aldehydes and their uses?
High level
Cross-linking functional groups to denature proteins and inactivate nucleic acids.
Glutaraldehyde disinfects and sterilizes
Formalin used in embalming and disinfection of rooms and instruments
122
Enzymes
a. What is the germicide classification?
b. Enzymes function by?
c. What are two types of antimicrobial enzymes and their targets?
d. Most of the eight antimicrobial chemicals we have discussed have low levels of selective toxicity.
High level to specific substrates
Denatures protein by digesting petoglycan cell wall of bacteria
1. Lysozyme used to reduce the number of bacteria in cheese 2. Prionzyme can remove prions on medical instruments
a. Antimicrobial enzymes act against microorganisms b. Human tears, saliva, and breast milk contain lysozyme
123
What are two methods for evaluating the efficiency of disinfectants and antiseptics
In use test
Use-dilution test
124
In use test
• Swabs taken from objects before and after application of disinfectant or
antiseptic
• Swabs inoculated into growth medium and incubated
• Medium monitored for growth
• Accurate determination of proper strength and application procedure for each specific situation
125
Use-dilution test
• Metal cylinders dipped into broth cultures of bacteria
• Contaminated cylinder immersed into dilution of disinfectant
• Cylinders removed, washed, and placed into tube of medium
• Most effective agents entirely prevent growth at highest dilution • Current standard test in the United States
• New standard procedure being developed
