1
Q
What are the major categories of microbial control?
A
- Physical agents
- Chemical agents
These methods are part of decontamination procedures that destroy or remove contaminants.
2
Q
What is the purpose of microbial control?
A
To destroy or remove contaminants
Contaminants are microbes that are undesirable or unwanted in a given place and time.
3
Q
Name the types of agents used in microbial control.
A
- Disinfectants
- Antiseptics
- Heat
- Radiation
These agents can be physical or chemical in nature.
4
Q
What is the highest resistance among microbial forms?
A
- Prions
- Bacterial endospores
Prions are proteinaceous infectious particles, while endospores are primarily from Bacillus and Clostridium.
5
Q
What forms of microorganisms have moderate resistance?
A
- Protozoan cysts
- Some fungal sexual spores (zygospores)
- Some viruses (naked viruses more resistant than enveloped)
These forms are generally more resistant to microbial control methods.
6
Q
Which bacteria are known for their increased resistance to microbial control agents?
A
- Mycobacterium
- Pseudomonas
- Acinetobacter
- Staphylococcus
These bacteria have thick cell walls or outer membranes that block disinfectants.
7
Q
What is the least resistance among microbial forms?
A
- Most bacterial vegetative cells
- Fungal spores (other than zygospores)
- Enveloped viruses
- Yeasts
- Protozoan trophozoites
These forms are generally easier to control with microbial agents.
8
Q
What factors influence the effectiveness of an antimicrobial agent?
A
Factors include:
* Concentration of the agent
* Duration of exposure
* Presence of organic matter
* Temperature
These factors can significantly impact how well an antimicrobial agent works.
9
Q
What are the targets of antimicrobial control agents?
A
- Bacterial cells
- Fungal cells
- Viruses
- Protozoa
Antimicrobial agents aim to disrupt the functions of these microorganisms.
10
Q
True or false: Microbial control methods have been a concern even before awareness of the germ-disease connection.
A
TRUE
Historical practices, such as burning clothing and using herbs, indicate early attempts at microbial control.
11
Q
What historical practices were used during the great plague pandemic for microbial control?
A
- Burying corpses in mass graves
- Burning clothing of plague victims
- Igniting aromatic woods
These practices were based on the belief that they would combat disease.
12
Q
What are the physical agents for microbial control?
A
- Mechanical removal methods
- Heat
- Radiation
- Filtration
These methods are used to eliminate or reduce microbial populations.
13
Q
Name the types of heat used in microbial control.
A
- Dry heat
- Moist heat
- Liquids
Each type of heat has different applications and effectiveness in microbial control.
14
Q
What is the goal of sterilization?
A
To destroy bacterial endospores
Endospores are highly resistant microbial entities, making them the primary target for sterilization processes.
15
Q
True or false: Endospores are easier to destroy than vegetative cells.
A
FALSE
Bacterial endospores are traditionally considered much more resistant than vegetative cells.
16
Q
What are the methods of microbial control mentioned?
A
- Disinfection
- Sterilization
- Antisepsis
Each method targets different levels of microbial life and has specific applications.
17
Q
Define disinfection.
A
Destruction or removal of vegetative pathogens but not bacterial endospores
Disinfection is usually applied to inanimate objects.
18
Q
Define sterilization.
A
Complete removal or destruction of all viable microorganisms
Sterilization is used on inanimate objects.
19
Q
What is antisepsis?
A
Chemicals applied to body surfaces to destroy or inhibit vegetative pathogens
Antisepsis is crucial for preventing infections during medical procedures.
20
Q
What is the problem with prions in microbial control?
A
Prions are extraordinarily resistant to heat, chemicals, and radiation
Most sterilization procedures are insufficient to destroy prions, requiring incineration or specific chemical treatments.
21
Q
What chemicals are most effective against prions?
A
- Sodium hydroxide
- Hypochlorite (bleach)
These chemicals can render prions noninfectious after significant exposure time.
22
Q
What is the relative resistance of bacterial endospores compared to vegetative cells?
A
Endospores are 18 times harder to destroy than vegetative cells
This highlights the importance of targeting endospores in sterilization processes.
23
Q
What is the temperature and radiation dosage required to kill endospores using moist heat?
A
120°C and 4,000 grays
These values indicate the conditions needed to effectively sterilize against the most resistant pathogens.
24
Q
Fill in the blank: Sterilization is the complete removal or destruction of all viable microorganisms, while disinfection targets only __________.
A
vegetative pathogens
This distinction is crucial for understanding different microbial control methods.
25
What is the definition of **sterilization**?
A process that destroys or removes all viable microorganisms, including viruses
## Footnote
An object is either sterile or not sterile; it cannot be slightly sterile.
26
What types of materials are generally subjected to **sterilization**?
* Inanimate objects
* Surgical instruments
* Syringes
* Commercially packaged foods
## Footnote
Sterilization is not practical for living tissues due to the harsh treatment required.
27
What is a **microbicidal agent**?
An antimicrobial agent aimed at destroying a certain group of microorganisms
## Footnote
Examples include bactericides, fungicides, and virucides.
28
What does the term **microbistasis** refer to?
A condition where microbes are temporarily prevented from multiplying but are not killed outright
## Footnote
Bacteriostatic and fungistatic agents are examples.
29
What is a **germicide**?
Any chemical agent that kills pathogenic microorganisms
## Footnote
Germicides can be used on inanimate materials or living tissue but often cannot kill resistant microbial cells.
30
What is the difference between **disinfection** and **sterilization**?
Disinfection destroys vegetative pathogens but not bacterial endospores; sterilization destroys all viable microorganisms
## Footnote
Disinfectants are typically used on inanimate objects.
31
What does the term **asepsis** mean?
Any practice that blocks the entry of infectious agents into sterile tissues
## Footnote
Aseptic techniques are crucial in healthcare to prevent infection.
32
What is **sanitization**?
Any cleansing technique that removes debris, soil, microorganisms, and toxins
## Footnote
Sanitization reduces the potential for infection and spoilage.
33
True or false: **Antisepsis** involves applying chemical agents directly to exposed body surfaces to destroy or inhibit vegetative pathogens.
TRUE
## Footnote
Examples include preparing skin with iodine or swabbing wounds with hydrogen peroxide.
34
Fill in the blank: A **bactericide** is a chemical that destroys _______ except for those in the endospore stage.
bacteria
## Footnote
Bactericides may or may not be effective on other microbial groups.
35
What is a **virucide**?
Any chemical known to inactivate viruses, especially on living tissue
## Footnote
Virucides are important in controlling viral infections.
36
Chemotherapy is a process of treating a disease with ________.
drugs
## Footnote
The host can be treated through various methods: oral, parenteral (IV, intramuscular, topical).
37
Prophylaxis is a process of treating a patient in order to ________ disease.
prevent
## Footnote
This approach aims to stop the onset of disease before it occurs.
38
A **bacteriostatic** substance ________ the growth of bacteria.
inhibits
## Footnote
If that substance is removed, bacteria may resume growth.
39
An **antibiotic** is a substance produced by one ________ to ________ or ________ another.
microbe
* inhibit
* kill
## Footnote
Antibiotics are typically produced in small quantities.
40
Pasteurized means ________-treated to ________ numbers of ________ and destroy ________ in liquids.
heat
* reduce
* microbes
* pathogens
## Footnote
This process is essential for food safety.
41
Microbial death is defined as the permanent loss of ________ capacity.
reproductive
## Footnote
This occurs even under optimum growth conditions.
42
Factors that microbial control depends on include ________.
* Temperature
* Environment
* pH
* Organic matter
* Presence of solvents
* Number of microbes
* Age and stage in life cycle
* Cell structure and function
## Footnote
Each factor can significantly affect microbial viability.
43
True or false: The **wall structure** of bacteria is important for their resistance.
TRUE
## Footnote
Gram-positive and Gram-negative bacteria exhibit different resistance levels.
44
Good contact and ________ power of treatment depends on several factors.
penetration
## Footnote
These factors include mode of action and type of radiation.
45
Antimicrobial agents can disrupt the **cell wall** by ________ structural integrity.
weakening
## Footnote
This leads to lysis of the microbial cell.
46
Examples of substances that damage the **cell membrane** include ________.
* Surfactants
* Alcohols
## Footnote
These substances create leaky spots in the membrane.
47
Inhibiting protein and nucleic acid synthesis involves blocking ________.
ribosomes
## Footnote
This stops peptide bonds and prevents replication.
48
Microbial targets include ________.
* Plasma membranes
* Proteins and enzymes
* DNA, RNA
* Cell walls
## Footnote
These targets are toxic to pathogens but not to the host.
49
The **spectrum of antimicrobial activity** can be classified as ________ or ________.
* Narrow spectrum
* Broad spectrum
## Footnote
Narrow spectrum affects a specific type of cell, while broad spectrum affects multiple types.
50
Microbial death usually occurs at a ________ rate.
constant
## Footnote
This allows for the plotting of a death curve.
51
Physical methods of control include ________.
* Heat (moist and dry)
* Cold temperatures
* Desiccation
* Radiation
* Filtration
## Footnote
These methods effectively control microbial populations.
52
Moist heat is more effective at ________ temperatures and shorter times.
lower
## Footnote
It coagulates and denatures proteins.
53
The **thermal death time (TDT)** is the shortest length of time required to kill all test microbes at a specified ________.
temperature
## Footnote
This measurement is crucial for sterilization processes.
54
Methods of moist heat control include ________.
* Sterilization with steam under pressure (autoclave)
* Non-pressurized steam (Tyndallization)
* Boiling water
* Pasteurization
## Footnote
Each method has specific applications and effectiveness.
55
Pasteurization kills non-spore-forming pathogens such as ________.
* Salmonella spp.
* Campylobacter jejuni
* Listeria monocytogenes
* Brucella spp.
* Coxiella burnetii
## Footnote
This process lowers overall microbe count without destroying food flavor.
56
What temperature and duration are used for **ultrapasteurized (sterile) milk** processing?
134°C, 2-5 sec
## Footnote
This process is known as UHT (Ultra High Temperature) processing.
57
Name the **non-spore-forming pathogens** targeted by pasteurization.
* Salmonella spp.
* Campylobacter jejuni
* Listeria monocytogenes
* Brucella spp.
* Coxiella burnetii
* Mycobacterium bovis, M. tuberculosis
* Various enteric viruses
## Footnote
These pathogens can cause milk-borne diseases.
58
True or false: **Dry heat** is more versatile than moist heat.
FALSE
## Footnote
Dry heat requires higher temperatures and longer times than moist heat.
59
What are the two main types of **dry heat** methods?
* Incineration
* Hot-air oven
## Footnote
Dry heat is essential for certain materials.
60
What is the temperature range for **dry ovens** used in sterilization?
150 - 180°C
## Footnote
Time can range from 12 minutes to 4 hours depending on load/material.
61
What is the mode of action of **incineration**?
Burns microbes to ashes and gas
## Footnote
Common uses include sterilizing inoculating loops/needles and disposing of medical waste.
62
What effect does **cold** have on microbes?
Slows microbial growth, does not reliably kill
## Footnote
Refrigeration inhibits most microbes, but some can survive for months.
63
Fill in the blank: **Freezing** preserves bacteria, viruses, and fungi for _______.
long-term storage
## Footnote
Some psychrotrophs can grow slowly even at freezing temperatures.
64
What is the effect of **desiccation (drying out)** on sensitive microbes?
Can kill sensitive microbes like Neisseria gonorrhoeae and Streptococcus pneumoniae
## Footnote
Gradual removal of water leads to metabolic inhibition.
65
What is **lyophilization**?
Combination of freezing + desiccation
## Footnote
It preserves microbial cultures for long-term storage.
66
What is the primary purpose of **filtration** in microbial control?
Physical removal of microorganisms
## Footnote
Fluid or air is strained through a filter, trapping microorganisms.
67
Name the **types of radiation** suitable for microbial control.
* Ionizing radiation
* Nonionizing radiation
## Footnote
Ionizing radiation includes gamma rays, X-rays, and cathode rays.
68
What is the purpose of **food irradiation**?
Used to kill bacterial pathogens, insects, and microbes that cause spoilage
## Footnote
It extends shelf life and reduces foodborne illnesses.
69
True or false: **Ionizing radiation** makes food radioactive.
FALSE
## Footnote
It does not make food radioactive and has a minor nutritional effect.
70
What is the primary target of **ionizing radiation**?
DNA
## Footnote
It causes mutations and breaks in DNA strands.
71
What are the common uses of **nonionizing UV radiation**?
* Air disinfection
* Water purification systems
* Surfaces in labs and food plants
## Footnote
It is used for disinfection rather than sterilization.
72
Define **disinfection**.
Destruction or removal of vegetative pathogens but not bacterial endospores
## Footnote
Usually used only on inanimate objects.
73
What are the **levels of chemical decontamination**?
* High-level germicides
* Intermediate-level
* Low-level
## Footnote
Each level targets different types of microbes.
74
What factors affect the **germicidal activity** of chemicals?
* Nature of the material being treated
* Degree of contamination
* Time of exposure
* Concentration of the chemical agent
## Footnote
Effectiveness depends on various factors.
75
What are the **target structures** affected by germicidal chemicals?
* Cell walls
* Cell membranes
* Proteins
* Nucleic acids
## Footnote
These structures are critical for microbial survival and function.
76
What factors affect the **effectiveness** of germicidal chemicals?
* Type and number of microbes present
* Nature of the surface or material being treated
* Length of exposure time
* Concentration & mode of action of the agent
## Footnote
Each factor plays a significant role in determining how effective a germicidal agent will be.
77
True or false: **Length of exposure** is critical for germicidal activity.
TRUE
## Footnote
Adequate contact time allows the chemical to penetrate and act on microbes.
78
What are the **common categories** of germicidal agents?
* Halogens
* Phenolics
* Chlorhexidine
* Alcohols
* Hydrogen peroxide
* Aldehydes
* Gases
* Detergents & soaps
* Heavy metals
* Dyes
## Footnote
These categories encompass a wide range of chemical agents used for microbial control.
79
What are the **common forms** of halogens used in germicidal activity?
* Chlorine gas (Cl₂)
* Hypochlorites (OCl⁻)
* Chloramines (NH₂Cl)
## Footnote
Chlorine and iodine are the most commonly used halogens.
80
What is the mode of action of **halogens** in germicidal activity?
* Forms hypochlorous acid (HClO) in water
* Oxidizes sulfhydryl groups and breaks disulfide bonds
* Denatures enzymes, damages DNA, RNA, lipids
## Footnote
These actions lead to the destruction of microbial cells.
81
What is the **effectiveness** of iodine (I₂) as a germicidal agent?
* Penetrates cells quickly
* Disrupts disulfide bonds in proteins
* Inhibits metabolic functions
* Effective against protozoan cysts
## Footnote
Iodine is less sensitive to organic matter than chlorine.
82
What are the **common types** of phenolics used in germicidal activity?
* Alkylated phenols (e.g., cresols)
* Chlorinated phenols (e.g., triclosan)
* Bisphenols
## Footnote
Phenolics are known for their effectiveness against a range of microbes.
83
What are the **advantages** of using phenolics as germicides?
* Active in presence of organic matter
* Detergent properties aid in cleaning
* Effective against vegetative bacteria and fungi
## Footnote
Phenolics have long-lasting effects on surfaces.
84
What is the **disadvantage** of using formaldehyde as a disinfectant?
* Highly toxic and carcinogenic
* Irritating to skin and mucous membranes
## Footnote
Due to these disadvantages, formaldehyde is rarely used in clinical settings today.
85
What is the **mode of action** of glutaraldehyde?
* Cross-links proteins via alkylation of amino acids
## Footnote
Glutaraldehyde is a broad-spectrum and rapid-acting disinfectant.
86
What are the **limitations** of using alcohols as germicides?
* Not sporicidal at room temperature
* Requires adequate contact time
## Footnote
Alcohols are effective against vegetative bacteria and enveloped viruses.
87
What is the **mode of action** of hydrogen peroxide?
* Decomposes into water + oxygen gas
* Bactericidal, virucidal, fungicidal, sporicidal at higher concentrations
## Footnote
Hydrogen peroxide can be used in liquid or vaporized form.
88
What are the **common aldehydes** used in microbial control?
* Glutaraldehyde
* Ortho-phthalaldehyde (OPA)
* Formaldehyde
## Footnote
Aldehydes act by cross-linking proteins and nucleic acids.
89
What is the **effectiveness** of chlorhexidine?
* Bactericidal for Gram-positive and gram-negative bacteria
* Not effective against spores
## Footnote
Chlorhexidine is widely used in hospitals to control MRSA and Acinetobacter.
90
What are the **disadvantages** of using gases like ethylene oxide for sterilization?
* Toxic, irritates lungs, eyes, mucous membranes
* Carcinogenic
* Requires aeration to remove residues post-sterilization
## Footnote
These factors limit the use of gases in certain settings.
91
What is the **mechanism** of action for detergents and soaps?
* Disrupts cell membranes
* Leads to cell lysis and death
## Footnote
Detergents act as surfactants that alter membrane permeability.
92
What is the definition of **sterilization**?
Process to destroy all viable microbes
## Footnote
Sterilization is essential in medical and laboratory settings.
93
What are **microbicidal agents**?
Antimicrobial agents aimed at destroying a certain group of microorganisms
## Footnote
Examples include bactericides, fungicides, virucides, and sporicidal agents.
94
What is the difference between **disinfection** and sterilization?
Disinfection uses a physical process or chemical agent to destroy vegetative pathogens but not all microbes
## Footnote
Sterilization aims to eliminate all forms of microbial life.
95
What is the **process** to destroy all viable microbes called?
Sterilization
## Footnote
This process ensures that all forms of microbial life are eliminated.
96
Define **microbicidal agents**.
* Antimicrobial agent aimed at destroying a certain group of microorganisms
* Includes bactericide, fungicide, virucide, sporicidal
## Footnote
These agents are specifically designed to target and eliminate specific types of microbes.
97
What is **disinfection**?
Use of a physical process or a chemical agent (disinfectant) to destroy vegetative pathogens but not bacterial endospores
## Footnote
Disinfection is crucial for reducing the risk of infection in various settings.
98
What does **antisepsis** involve?
Application of chemical agents (antiseptics) directly to exposed body surfaces, wounds, and surgical incisions to destroy or inhibit vegetative pathogens
## Footnote
Antiseptics are essential in preventing infections during medical procedures.
99
Which **heavy metals** are routinely used for their antimicrobial properties?
* Mercury
* Silver
## Footnote
These metals exhibit oligodynamic action, meaning they can be effective in very small amounts.
100
What is the **mechanism** of heavy metals in microbial control?
* Bind to functional groups on proteins
* Inactivate enzymes → halts metabolism
## Footnote
This mechanism is effective against a variety of microorganisms.
101
What are the **common formulations** of heavy metals used?
* Aqueous solutions
* Tinctures
* Ointments
* Soaps
## Footnote
These formulations are used in various applications, including medical and industrial settings.
102
True or false: Heavy metals are **not toxic** to humans.
FALSE
## Footnote
Heavy metals, especially mercury, can be toxic and may cause allergic reactions.
103
What is the primary use of **dyes** in microbiology?
* Staining microbes
* Selective agents in media
## Footnote
Dyes help in identifying and differentiating microorganisms in laboratory settings.
104
Name two examples of **aniline dyes**.
* Crystal violet
* Malachite green
## Footnote
These dyes are effective against gram-positive bacteria and some fungi.
105
What is the **antimicrobial action** of acridine dyes?
* Used in antisepsis and wound treatment
* Insert into nucleic acids → cause mutations
* May interfere with cell wall synthesis
## Footnote
Acridine dyes are utilized in both medical and veterinary applications.
106
What is the effect of **extreme pH** on microbes?
Can kill or inhibit microbes
## Footnote
Extreme pH levels disrupt microbial proteins, leading to antimicrobial effects.
107
What are common **agents** that have extreme pH?
* Ammonium hydroxide
* Sodium hydroxide (NaOH)
## Footnote
Sodium hydroxide is one of the few agents that can destroy prions.
108
What is the role of **organic acids** in food preservation?
Prevent spore germination, bacterial, and fungal growth
## Footnote
Organic acids are generally recognized as safe (GRAS) for consumption.
109
What is **sanitization**?
Any cleansing technique that removes microorganisms from inanimate surfaces to reduce the potential for infection and spoilage
## Footnote
Sanitization is crucial in maintaining hygiene in various environments.
110
Define **degermation**.
Reduction of microbial load from living tissue by mechanical means
## Footnote
This process is often used in medical settings to prepare skin for surgery.
111
What does **asepsis** refer to?
Techniques that prevent the entry of microorganisms into sterile tissues
## Footnote
Aseptic techniques are vital in surgical procedures to prevent infections.
112
What is the definition of **decontamination**?
The destruction, removal, or reduction in number of undesirable microbes
## Footnote
Decontamination is a key process in infection control.
113
What has highest resistance?
Prions: proteinaceous infectious particles; bacterial endospores, primarily from bacteria in the genera Bacillus and Clostridium
114
What has moderate resistance?
- Protozoan cysts; some fungal sexual spores (zygospores); some viruses
In general naked viruses are more resistant than enveloped forms
-Mycobacterium w/ thick cell walls that block entrance of disinfectants
- cell walls of pseudomonas, acinetobacter, and other gram (-) have an outer membrane that prevents penetration
- staphylococcus species are most heat and chemical resistant of all bacteria due to thick peptidoglycan walls
115
Least resistant
Most bacterial vegetative cells; fungal apores(other than zygospores) and hyphae; enveloped viruses;yeasts;and protozoan trophozoites
116
What is most sterilization performed with?
Physical agent such as heat, a few chemicals called sterilants can be classified as sterilizing agents because of their ability to destroy spores
117
Some anti microbial agents eliminate only the susceptible ___ states of microorganisms but do not destroy the more resistant ___ and ___ stages
Vegetative
Endospore, cyst
118
Most of the infectious diseases of humans and animals are caused by ____ forming microbes
Non spore
119
Fungicide
Chemical that can kill fungal spores, hyphae, and yeasts
120
Virucude
Chemical known to inactivate viruses, especially on living tissue
121
Sporicidal agent
Destroy bacterial endospores which makes it a sterilizing agent
122
Microbistasis
Microbes are temporarily prevented from multiplying but are not killed outright
123
Bacteriostatic agents
Prevent the growth of bacteria on tissues or on objects in the environment , and fungistatic chemicals inhibit fungal growth
124
Materials used to control microorganisms in the body (antiseptics and drugs) often have ___ effects because many microbicidal compounds are highly toxic to human cells
Microbistatic
125
Germicide also called …
Microbicide
126
Germicide
Any chemical agent that kills pathogenic microorganisms
127
128
What can a germicide be used on
Inanimate(non living) materials or on living tissue , but it ordinarily cannot kill resistant microbial cells
129
Disinfection
Use of a physical process or a chemical agent, can destroy vegetative cells not endospores
130
What are disinfectants normally used on
Inanimate objects because at the concentrations required to be effective , they can be toxic to living tissue
131
Disinfection processes can also remove the harmful products of ___ from materials
Microorganisms
132
Sepsis
Growth of microorganisms in the blood and other tissues
133
Asepsis
Any practice that blocks the entry of infectious agents into sterile tissue and thus prevents infection (antiseptics)
134
Where are antiseptics applied
Exposed body surfaces , wounds, and surgical incisions to destroy or inhibit vegetative pathogens
135
Sanitization
Cleansing technique that removes debris, soil, and microorganism and toxins and in this way reduces potential for infection and spoilage
136
What are the most employed sanitizers
Soaps and detergents
137
With living tissues the reduction in microbial load through mechanical means is referred to as
Degermation
138
What does the process of degermation usually involve
Scrubbing the skin or immersing in chemicals or both. Microorganisms are removed both mechanically and indirectly by emulsifying the oils that coat the skin and provide a habitat for their growth
139
Lethal agents such as radiation and chemicals do not necessarily alter the overt ____ of microbial cells
Appearance
140
Most practical way to detect damage is to determine if a microbial cell can still ___ when exposed to a suitable environment
Reproduce
141
Because many microbicidal agents target the cells metabolic processes, active cells (younger, rapidly dividing) tend to die more ___
Quickly than those that are less metabolically active (older, dormant)
142
The effectiveness of a particular agent is governed by several factors besides time. These additional factors influence the action of antimicrobial agents
1 # of microorganisms. Higher load of contaminants requires more time to destroy
2. Nature of microorganisms in population. Target population is not a single species of microbe but a mixture of bacteria, fungi, etc
3. Temp and pH of environment
4. Concentration of the agent
5. Mode of action of agent (how it kills)
6. Presence of solvents, interfering organic matter, and inhibitors. Saliva, blood, and feces can inhibit actions
143
An antimicrobial agents adverse effect on cells is known as its___(or mechanism) ____
Mode of action
144
Agents affect one or more ___ ___ , inflicting damage progressively until the cell is no longer ___
Cellular targets
Viable
145
Antimicrobial have a range of ___ ___, with the agents are __ selective in their targeting tending to be effective against the widest range if ___
Cellular targets
Least
Micorbes
146
More selective agents (drugs for example ) tend to target only a ___ cellular component and are much more restricted in their effect on ___
Single
Microbes
147
The cellular targets of physical and chemical agents fall into four general categories
1. Cell walls
2. Cell membranes
3. Protein and nucleic acid synthesis
4. Protein structure and function
148
What does the cell wall maintain?
Structural integrity of bacterial and fungal cells
149
How do several types of chemical agents damage the cell wall?
By blocking its synthesis, digesting it, or breaking down its surface
150
A cell deprived of a cell becomes ___ and is ___
Fragile
Lysed
Very easily
151
All microorganisms have a cell membrane composed of ?
Lipids and proteins, and some viruses may have outer membranous envelope
152
If a cell membrane is disrupted, a cell loses its?
Selective permeability and can neither prevent the loss of vital molecules more bar the entry of damaging chemicals
This leads to cell death
153
What do chemicals called surfactants work as?
Microbicidal agents because they lower the surface tension of cell membranes
154
Are surfactants polar?
Yes such as detergents with hydrophilic and hydrophobic regions that can bind to the lipid layer and penetrate the internal hydrophobic regions membranes
155
What do surfactants cause the opening of
Opens up tight interface leaving leaky spots that allow harmful chemicals to seep into cell and important ions to seep out
156
What do alcohols relate to? And what do they destroy?
Relate to surfactants
Dissolve membrane lipids and stripping membranes away from cells
157
What does microbial life depend on?
Supply of proteins to function as enzymes and structural molecules
Proteins synthesized on ribosomes during translation
158
What do certain drugs bind to?
Ribosomes of bacteria in a way that stops peptide bonds from forming
159
Many of the drugs used to treat infections are chemicals that block?
Protein synthesis in microbes without adversely affecting human cells
160
Are nucleic acids necessary for the continued functioning of microbes?
Yes
161
DNA must be regularly replicated and transcribed in growing cells and any agent that either impedes these processes or changes the genetic code is potentially ___
Antimicrobial
162
What do some agents bind irreversibly to?
DNA, preventing both transcription and translation, whereas others are mutagenic agents
163
What can cause mutations
Gamma, ultraviolet, or X radiation causes mutations that result in permanent inactivation of DNA
Chemicals such as formaldehyde and ethylene oxide also interfere w/ DNA and RNA
164
A microbial cell contains large quantities of proteins that only function if they are in a __ shape called the ___ __
3D
Native state
165
Desaturation
Bonds tha maintain the secondary and tertiary structure of protein are broken
166
When happens when bonds are broken in denaturation
Cause protein to unfold or create random irregular loops and coils
167
What is one way to denature proteins?
Coagulation by moist heat
168
What is another way you can denature proteins
Chemicals such as strong organic solvents (alcohols, acids) also coagulate proteins
169
A few antimicrobial agents, such as metallic ions, attach to the ___ site of protein and prevent it from interacting with its ___ substrate
Active
Correct
170
Most prominent among antimicrobial physical agents is ___
Heat
171
Less widely agents include
Radiation and filtration
172
Temperatures that exceed the maximum growth temperature are ?
Temperatures that are below minimum growth temp are?
Microbicidal
Microbistatic
173
Two physical states of heat used in microbial control are __ and ___
Moist and dry
174
How does moist heat occur?
Form of hot water, boiling water, or steam
175
What is the temp of moist heat
60°c to 135°c
176
What is dry heat
Denotes air w/ low moisture content that has been heated by a flame or electric heating coil
177
What is the temperature of dry heat
160°c to several thousand degrees Celsius
178
Moist heat operates at ____ temperatures and ___ exposure times to achieve the same effectiveness as dry heat
Lower
Shorter
179
Although many cellular structures are damaged by moist heat, its most microbicidal effects are the ___ and ___ of proteins, which quickly and permanently halt cellular metabolism
Coagulation
Denaturation
180
Dry heat w/ a moderate temperature ___ the cell, removing the ___ necessary to metabolic reactions, it alters protein ___
Dehydrates
Water
Structure
181
What does the lack of water sometimes do to proteins when dry heat is occurring
Increases the stability of some protein conformations, necessitating the use of higher temp when dry heat is employed, this is a form of microbial control
182
At very high heat what does dry heat do to cells?
Oxidizes cells, burning them to ashes
Usually used in laboratories when a loop is flamed or incineration
183
Thermal death time TDT
Shortest length of time required to kill all test microbes at a specified temp
184
Thermal death point TDP
Lowest temp required to kill all microbes in a sample in 10 minutes
185
Many perishable substances are processed with __ heat
Moist
186
The chosen heat treatment must render the product free of agents of ___ or ___
Spoilage
Disease
187
4 ways moist heat is employed to control microbes are?
1. Steam under pressure
2. Non pressurized steam
3. Boiling water
4. Pasteurization
188
How to raise the temperature of steam ?
Expose it to increased pressure
189
What is an autoclave
Makes pressure temp combinations with this special device that can subject pure steam to pressures greater than 1 atmosphere
190
How is sterilization achieved in an autoclave
Steam condenses against the objects in the chamber and gradually raises the temperature
191
Most efficient pressure temp combination for achieving sterilization (autoclave)
15psi which yields 121°c
Don’t go higher which might harm the product
192
What does the duration of the process of sterilization in the autoclave depend on?
Bulkness of the items in the load and how full the chamber is
10min for light loads
40min for heavy loads
Avg time is 20min
193
What is used in moist heat control for steam under pressure ?
Autoclave
194
Selected substances that cannot withstand the high temperature of the autoclave can be subjected to? (Nonpressurized steam, moist heat control)
Intermittent sterilization also called tyndallization
195
What does intermittent sterilization/tyndallization require?
Chamber to hold th materials and a reservoir for boiling water
196
What are items in the chamber for non pressurized steam (moist heat) exposed to?
Free flowing steam for 24hrs and then again subjected to steam treatment
Cycle repeated for 3 days in a row
197
Since the chamber for nonpressurized steam (moist heat control) doesn’t exceed 100°c, highly resistant spores that do not ___ could survive after _ days of treatment
Germinate
3
198
Boiling water: disinfection for moist heat control
Boiling water bath or chamber can quickly decontaminate items
Only disinfects but not sterilize
199
What does exposing items to boiling water for 30 min kill?
N
Non spore forming pathogens , including resistant species such as the tubercle bacillus and staphylococci
200
What is the greatest disadvantage boiling water
Items can easily be decontaminated when removed from water
201
Pasteurization: Disinfection of beverages (moist heat control)
Technique of applying heat to consumable liquids to kill potential agents of infection and spoilage, while at the same time retaining the liquids flavor and food value
202
What is a widely used pasteurization technique ?
Flash method , exposes the liquid to heat exchangers at 71.6°c for 15sec
It doesn’t change flavor and nutrient content
Effective against resistant pathogens such as coxiella and mycobacterium
203
What do the pasteurization techniques not destroy?
Don’t kill endospores or thermoduric microbes (mostly nonpathogenic lactobacilli, micrococci, and yeasts)
204
One important aim in pasteurization is to prevent what?
Transmission of milk borne diseases from infected cows or milk handlers
205
Is dry heat more used than moist heat?
No but it does have important sterilization applications
206
The temperatures and times employed in dry heat vary according to the particular method, in general they are ___ than with moist heat
Greater
207
Incineration (dry heat)
Flame or electric heating coil is perhaps the most rigorous of all heat treatments (Bunsen burner)
Intense heat ignites and reduces microbes and other substances to ashes and gas
208
What is incineration restricted to?
It’s fast and effective but limited to metals and heat resistant glass materials
209
Hot air oven (dry heat)
Dry heat sterilization
Electric w coils that radiate heat
Cycle can take up to 12min to 4hr tom complete and involve temp of 150°to 180°c
210
What is the benefit of cold treatment
Slow growth of cultures and microbes in food and other perishable materials during processing and storage
211
Are some sensitive microbes killed by cold temperatures?
Yes but most are not adversely affected by gradual cooling, long term refrigeration or deep freezing
212
What temperatures preserve cultures?
-70°c to -135°c , provide an environment that can preserve cultures of bacteria, viruses, and fungi for long periods
213
What are some pathogens that are able to survive in refrigerator ?
Staphylococcus aureus, clostridium species (sporeformers): listeria: and several types of yeasts, mold, and viruses
214
Most vegetative cells directly exposed to normal room air gradually become dehydrated or ___
Desiccated
215
Many viruses (especially non enveloped) and fungal spores can also withstand periods of __ in room temp
Desiccation
216
Desiccation can be a valuable way to preserve foods because it greatly reduces the amount of ___ available to support microbial growth
Water
217
Combination of freezing and drying aka ___ is a common method of preserving microorganisms and other cells in a viable state for many years
Lyophilization
218
What is the process of lyophilization ?
Pure cultures are frozen instantaneously and exposed vacuum that rapidly removes water
This method avoids formation of ice crystals that would damage the cells
219
What should chilling, freezing, and desiccation should not be constructed as methods of what?
Disinfection or sterilization
Because their antimicrobial effects are erratic and uncertain and one cannot be sure that pathogens subjected to them have been killed
220
What is **radiation** defined as?
Energy emitted from atomic activities and dispersed at high velocity through matter or space
## Footnote
Radiation is characterized by a range of wavelengths known as the electromagnetic spectrum.
221
Name the types of radiation suitable for **microbial control**.
* Gamma rays
* X rays
* Ultraviolet radiation
## Footnote
These types of radiation can serve as antimicrobial agents.
222
What is the process of **irradiation**?
Bombardment with radiation at the cellular level
## Footnote
This process leads to physical effects on microbes.
223
What happens when **ionizing radiation** ejects orbital electrons from an atom?
It causes ions to form
## Footnote
One of the most sensitive targets for ionizing radiation is DNA, leading to mutations.
224
What are the **secondary lethal effects** of ionizing radiation?
* Chemical changes in organelles
* Production of toxic substances
## Footnote
These effects can occur alongside mutations in DNA.
225
How does **nonionizing radiation** differ from ionizing radiation?
It excites atoms without ionizing them
## Footnote
Nonionizing radiation leads to abnormal bonds within molecules such as DNA.
226
What are examples of **ionizing radiation**?
* Gamma rays
* X rays
* Cathode rays
## Footnote
These types of radiation have applications in sterilization.
227
What is the significance of **cold sterilization**?
Sterilization in the absence of heat
## Footnote
Ionizing radiation is a type of cold sterilization effective for heat-sensitive materials.
228
What devices emit **ionizing rays**?
* Gamma-ray machines
* X-ray machines
* Cathode-ray machines
## Footnote
These devices irradiate items for sterilization.
229
What is the dosage of radiation measured in?
Grays
## Footnote
The older term for this measurement was rads.
230
What is the range of exposure for ionizing radiation in **kilograys**?
5 to 50 kilograys
## Footnote
A kilogray is equal to 1,000 grays.
231
Which type of ionizing radiation is the most penetrating?
Gamma rays
## Footnote
X rays are intermediate, and cathode rays are the least penetrating.
232
What is **irradiation** used for in food processing?
* Killing bacterial pathogens
* Eliminating insects and worms
* Inhibiting sprouting of white potatoes
* Reducing spoilage and improving shelf life
## Footnote
Foods such as flour, pork, ground beef, fruits, and vegetables have been subject to irradiation for over 50 years.
233
True or false: **Irradiated food** can make food radioactive.
FALSE
## Footnote
The irradiation process does not make food radioactive, and extensive studies have shown no ill effects from consuming irradiated food.
234
What small nutrient decrease may occur due to **irradiation**?
Thiamine (vitamin B1)
## Footnote
The decrease in thiamine is small enough to be considered inconsequential.
235
List some **foods that do not irradiate well**.
* Egg whites (become milky)
* Alfalfa seeds (do not germinate properly)
## Footnote
Certain foods are not good candidates for irradiation treatment.
236
What are the estimated benefits of irradiating **50% of meat and poultry** in the U.S.?
* 900,000 fewer cases of infection
* 8,500 fewer hospitalizations
* 350 fewer deaths each year
## Footnote
These estimates highlight the potential impact of irradiation on public health.
237
What pathogens does irradiation help reduce in **beef and chicken**?
* E. coli
* Salmonella
## Footnote
Irradiation is approved for reducing these bacterial pathogens in meat products.
238
What is a key requirement for selling **irradiated food** to consumers?
Clear labeling that irradiation has been used
## Footnote
This ensures consumers are informed about the treatment applied to the food.
239
What types of **medical products** can be sterilized using ionizing radiation?
* Drugs
* Vaccines
* Medical instruments (especially plastics)
* Other delicate materials
## Footnote
This field is rapidly expanding due to the advantages of speed and effectiveness.
240
What is the wavelength range of **Ultraviolet (UV) radiation**?
Approximately 100 nm to 400 nm
## Footnote
UV radiation is most lethal from 240 nm to 280 nm, with a peak at 260 nm.
241
What is the source of UV rays commonly used in practice?
Germicidal lamp
## Footnote
This lamp generates radiation at 254 nm.
242
True or false: **UV radiation** is more penetrating than ionizing radiation.
FALSE
## Footnote
UV radiation has a lower energy state and is not as penetrating as ionizing radiation.
243
What must happen for UV radiation to have a full disinfecting effect?
The object must be directly exposed to it
## Footnote
UV radiation passes readily through air and slightly through liquids, but poorly through solids.
244
What specific molecular damage occurs in DNA due to UV radiation?
Formation of **pyrimidine dimers**
## Footnote
These abnormal linkages occur between adjacent thymine and cytosine bases.
245
What are the consequences of pyrimidine dimers on DNA?
* Inhibition of growth
* Cellular death
## Footnote
These dimers interfere with normal DNA replication and transcription.
246
What toxic products are generated by UV radiation that disrupt cells?
Free radicals
## Footnote
These highly reactive molecules bind to DNA, RNA, and proteins, interfering with essential cell processes.
247
What types of cells can UV rays effectively destroy?
* Fungal cells and spores
* Bacterial vegetative cells
* Protozoa
* Viruses
## Footnote
Bacterial spores are about 10 times more resistant to radiation than vegetative cells.
248
How can bacterial spores be killed by UV radiation?
By increasing the time of exposure
## Footnote
This compensates for their higher resistance to radiation.
249
What is the primary aim of **ultraviolet radiation** in disinfection?
Disinfection
## Footnote
Ultraviolet radiation is usually aimed more at disinfection than at sterilization.
250
Ultraviolet disinfection can reduce airborne microbes by as much as _______.
99%
## Footnote
Germicidal lamps can cut down on the concentration of airborne microbes significantly.
251
Name three applications of **ultraviolet disinfection**.
* Reducing postoperative infections
* Preventing transmission of infections by respiratory droplets
* Curtailing growth of microbes in food-processing plants
## Footnote
Ultraviolet disinfection has proved effective in various settings.
252
What special equipment is required for **ultraviolet irradiation** of liquids?
Equipment to spread the liquid into a thin, flowing film
## Footnote
This method is used to treat water and purify other liquids as an alternative to heat.
253
What types of surfaces can be disinfected with **UV light**?
* Solid, nonporous materials (walls, floors)
* Meat
* Nuts
* Tissues for grafting
* Drugs
## Footnote
UV light can successfully disinfect various surfaces.
254
True or false: **Ultraviolet radiation** has good penetration through solid materials.
FALSE
## Footnote
UV has poor powers of penetration through materials such as glass, metal, cloth, plastic, and paper.
255
What are some harmful effects of **overexposure** to UV radiation on human tissues?
* Sunburn
* Retinal damage
* Cancer
* Skin wrinkling
## Footnote
These harmful results occur only with direct exposure to UV rays.
256
What is **filtration** in the context of removing microbes?
A physical removal process
## Footnote
Filtration is effective for removing microbes from air and liquids.
257
What materials are commonly used in **modern microbiological filters**?
* Cellulose acetate
* Polycarbonate
* Plastic materials (Teflon, nylon)
## Footnote
These materials allow for careful control and standardization of pore size.
258
What is the range of pore diameters in filters used for microbial removal?
From coarse (8 um) to ultrafine (0.02 um)
## Footnote
This range permits selection of the minimum particle size to be trapped.
259
What can filters with even smaller pore diameters achieve?
True sterilization by removing viruses
## Footnote
Some filters can even remove large proteins.
260
What is the process of **filtration sterilization** used for?
* Preparing liquids that cannot withstand heat
* Sterilizing serum and blood products
* Vaccines
* Drugs
* IV fluids
* Enzymes
* Media
## Footnote
Filtration sterilization is crucial for substances sensitive to heat.
261
Name two products that can be sterilized using **filtration** without altering their flavor.
* Milk
* Beer
## Footnote
Filtration serves as an alternative method for sterilizing these beverages.
262
What is a significant application of filtration in **water purification**?
Filtering out particulate impurities
## Footnote
This helps prevent severe reactions in the body caused by contaminants.
263
True or false: **Filtration** removes soluble molecules (toxins) that can cause disease.
FALSE
## Footnote
Filtration does not remove soluble molecules, which can still pose health risks.
264
What type of filters are used to remove **airborne contaminants** in hospitals?
High-efficiency particulate air (HEPA) filters
## Footnote
HEPA filters provide a flow of sterile air to hospital rooms and sterile environments.
265
When did **chemical control of microbes** emerge as a serious science?
Early 1800s
## Footnote
Physicians used chloride of lime and iodine solutions for treating wounds and handwashing before surgery.
266
Approximately how many different **antimicrobial chemical agents** are manufactured today?
10,000
## Footnote
About 1,000 of these are used routinely in healthcare and home environments.
267
What are some common uses of **antimicrobial chemicals**?
* Kill germs
* Disinfect
* Antisepticize
* Clean and sanitize
* Deodorize
* Fight plaque
* Purify the air
## Footnote
The abundance of products reflects a preoccupation with eliminating microbes.
268
What states can **antimicrobial chemicals** occur in?
* Liquid
* Gaseous
* Solid
## Footnote
They serve various functions such as disinfectants, antiseptics, and preservatives.
269
What is an **aqueous solution**?
A solution containing pure water as the solvent
## Footnote
Antimicrobial chemicals are often dissolved in water or alcohol.
270
What are some desirable qualities in a **germicide**?
* Rapid action in low concentrations
* Solubility in water or alcohol
* Broad-spectrum microbicidal action
* Penetration of inanimate surfaces
* Resistance to inactivation by organic matter
* Noncorrosive or nonstaining properties
* Sanitizing and deodorizing properties
* Affordability and availability
## Footnote
No chemical currently fulfills all requirements, but chlorhexidine and hydrogen peroxide come close.
271
What are the **three levels of chemical decontamination procedures**?
* High-level germicides
* Intermediate-level germicides
* Low-level germicides
## Footnote
Each level corresponds to the effectiveness against different types of microbes.
272
What do **high-level germicides** kill?
Endospores
## Footnote
They are sterilants used for medical devices that cannot be heat-sterilized.
273
What do **intermediate-level germicides** kill?
* Fungal spores
* Resistant pathogens (e.g., tubercle bacillus)
* Viruses
## Footnote
Used to disinfect items that contact mucous membranes but are noninvasive.
274
What do **low-level germicides** eliminate?
* Vegetative bacteria
* Vegetative fungal cells
* Some viruses
## Footnote
Used for cleaning materials that touch skin surfaces but not mucous membranes.
275
What factors affect the **germicidal activities** of chemical agents?
* Numbers and kinds of microbes present
* Kinds of materials being treated
* Time of exposure required
* Strength and mode of action of the agent
## Footnote
Effectiveness depends on these factors, particularly exposure time and agent strength.
276
True or false: **Length of exposure** is not important for the effectiveness of chemical agents.
FALSE
## Footnote
Adequate contact time is necessary for the chemical to penetrate and act on microbes.
277
What can hinder effective disinfection when an item is contaminated?
* Common biological matter
* Serum
* Blood
* Saliva
* Pus
* Fecal material
* Urine
## Footnote
Large amounts of organic material can hinder penetration and reduce a chemical's activity.
278
What is the effect of adequate cleaning of instruments and reusable materials on germicides?
Ensures better effectiveness of germicide or sterilant
## Footnote
Proper cleaning allows the germicide or sterilant to accomplish its intended job.
279
How is a chemical's strength or concentration expressed?
* Various ways depending on convention
* Method of preparation
## Footnote
The content of many chemical agents can be formulated in more than one way.
280
What is an example of a common laboratory phenolic disinfectant and its dilution ratio?
Lysol, diluted 1:200
## Footnote
One part of the chemical is added to 200 parts of water by volume.
281
How are solutions like chlorine expressed when effective in very diluted concentrations?
Parts per million (ppm)
## Footnote
This method is used for solutions that are effective at low concentrations.
282
In percentage solutions, how is the solute added to the solvent?
By weight or volume to achieve a certain percentage
## Footnote
Alcohol is commonly used in percentages ranging from 50% to 95%.
283
What is the general relationship between solution concentration and germicidal effectiveness?
Lower dilution or higher percentage tends to be more germicidal
## Footnote
However, expense and potential toxicity can necessitate using the minimum strength that is effective.
284
Name some prominent categories of chemical agents used for antimicrobial purposes.
* Halogens
* Phenolic compounds
* Alcohols
* Oxidizers
* Aldehydes
* Gases
* Detergents
* Heavy metals
## Footnote
These groups are widely used in medicine and commerce.
285
What are the **halogens**?
* Fluorine
* Bromine
* Chlorine
* Iodine
## Footnote
Halogens are a group of nonmetallic elements with similar chemical properties, primarily exerting their antimicrobial effect in the nonionic state.
286
Which halogens are routinely used in **germicidal preparations**?
* Chlorine
* Iodine
## Footnote
Fluorine and bromine are difficult to handle and not more effective than chlorine and iodine.
287
What is the primary action of halogens in antimicrobial applications?
* Microbicidal
* Sporicidal
## Footnote
Halogens are effective components of disinfectants and antiseptics due to their ability to kill microorganisms.
288
What percentage of all antimicrobial chemicals currently marketed contain **halogens**?
Nearly one-third
## Footnote
Halogens are significant active ingredients in antimicrobial formulations.
289
What are the major forms of **chlorine** used in microbial control?
* Liquid chlorine
* Gaseous chlorine
* Hypochlorites
* Chloramines
## Footnote
Chlorine has been used for disinfection and antisepsis for approximately 200 years.
290
What does hypochlorous acid (HClO) do to enzymes?
* Oxidizes sulfhydryl (SH) groups
* Breaks disulfide (S—S) bridges
## Footnote
This results in permanent denaturation of enzymes and suspension of metabolic reactions.
291
How long does it usually take for chlorine to kill almost all microorganisms?
30 minutes
## Footnote
Endospores may require several hours for complete death.
292
What factors reduce the effectiveness of chlorine compounds?
* Exposure to light
* Alkaline pH
* Excess organic matter
## Footnote
These conditions make chlorine compounds less effective and relatively unstable.
293
What is the appearance of **iodine** when dissolved in water?
Brown-colored solution
## Footnote
Iodine is a pungent blue-black element.
294
What are the **halogens**?
* Fluorine
* Bromine
* Chlorine
* Iodine
## Footnote
Halogens are a group of nonmetallic elements with similar chemical properties, primarily exerting their antimicrobial effect in the nonionic state.
295
Which halogens are routinely used in **germicidal preparations**?
* Chlorine
* Iodine
## Footnote
Fluorine and bromine are difficult to handle and not more effective than chlorine and iodine.
296
What is the primary action of halogens in antimicrobial applications?
* Microbicidal
* Sporicidal
## Footnote
Halogens are effective components of disinfectants and antiseptics due to their ability to kill microorganisms.
297
What percentage of all antimicrobial chemicals currently marketed contain **halogens**?
Nearly one-third
## Footnote
Halogens are significant active ingredients in antimicrobial formulations.
298
What are the major forms of **chlorine** used in microbial control?
* Liquid chlorine
* Gaseous chlorine
* Hypochlorites
* Chloramines
## Footnote
Chlorine has been used for disinfection and antisepsis for approximately 200 years.
299
What does hypochlorous acid (HClO) do to enzymes?
* Oxidizes sulfhydryl (SH) groups
* Breaks disulfide (S—S) bridges
## Footnote
This results in permanent denaturation of enzymes and suspension of metabolic reactions.
300
How long does it usually take for chlorine to kill almost all microorganisms?
30 minutes
## Footnote
Endospores may require several hours for complete death.
301
What factors reduce the effectiveness of chlorine compounds?
* Exposure to light
* Alkaline pH
* Excess organic matter
## Footnote
These conditions make chlorine compounds less effective and relatively unstable.
302
What is the appearance of **iodine** when dissolved in water?
Brown-colored solution
## Footnote
Iodine is a pungent blue-black element.
303
What is the **basic structure** of phenolic compounds?
Aromatic ring with various side groups such as Cl and CH3
## Footnote
Examples include o-cresol, p-cresol, chlorophene, and hexachlorophene.
304
What is the **mode of action** of chlorhexidine?
Targets cell membranes by lowering surface tension and causing denaturation of proteins
## Footnote
It is effective against gram-positive and gram-negative bacteria but inactive against spores.
305
What are the **advantages** of chlorhexidine over other antiseptics?
* Mildness
* Low toxicity
* Rapid action
* Not absorbed into deeper tissues
## Footnote
It is the antiseptic cleanser of choice for controlling Staphylococcus MRSA and Acinetobacter outbreaks in hospitals.
306
Which **alcohols** are suitable for microbial control?
* Ethyl alcohol
* Isopropyl alcohol
## Footnote
Methyl alcohol is not particularly microbicidal.
307
What is the **mechanism of action** of alcohols at concentrations of 50% and higher?
Dissolves membrane lipids, disrupts cell surface tension, and compromises membrane integrity
## Footnote
Alcohol denatures proteins through coagulation in alcohol-water solutions of 50% to 95%.
308
True or false: Alcohol shows greater microbicidal activity at **100% concentration** than at **70% concentration**.
FALSE
## Footnote
Alcohol is more effective at 70% concentration because water is needed for proteins to coagulate.
309
What happens to alcohol at **100% concentration**?
Dissolves cell membranes and inhibits cell growth but is generally not a protein coagulant
## Footnote
Absolute alcohol (100%) lacks the necessary water for protein coagulation.
310
What is the primary limitation of **alcohol** in germicidal applications?
Does not destroy bacterial spores at room temperature
## Footnote
Alcohol can destroy resistant vegetative forms, including tuberculosis bacteria and fungal spores, with adequate exposure time.
311
True or false: **Alcohol** is more effective against nonenveloped viruses than enveloped viruses.
FALSE
## Footnote
Alcohol tends to inactivate enveloped viruses more readily due to its surfactant effect on the envelope.
312
What is the chemical formula for **hydrogen peroxide**?
H₂O₂
## Footnote
Hydrogen peroxide is a colorless, caustic liquid that decomposes into water and oxygen gas.
313
What are the germicidal effects of **hydrogen peroxide** attributed to?
Direct and indirect actions of oxygen
## Footnote
Oxygen forms hydroxyl free radicals (-OH), which are highly toxic and reactive to cells.
314
What types of microorganisms does **hydrogen peroxide** affect?
* Bactericidal
* Virucidal
* Fungicidal
* Sporocidal (in higher concentrations)
## Footnote
Most microbial cells produce catalase to inactivate hydrogen peroxide, but it cannot neutralize the amount penetrating during disinfection.
315
What has led to the development of chambers that circulate combinations of **peroxide** and **peracetic acid**?
Need for heat-free rapid sterilization of small medical devices
## Footnote
These chambers enhance the sterilization process for medical equipment.
316
What is a use of **vaporized hydrogen peroxide**?
Effective as an environmental sterilant
## Footnote
It is used in decontaminating large spaces and objects.
317
What are **aldehydes**?
Organic substances bearing a CHO functional group on the terminal carbon
## Footnote
Aldehydes are strong reducing agents used in microbial control.
318
Name the two most commonly used **aldehydes** in microbial control.
* Glutaraldehyde
* Ortho-phthaldehyde
## Footnote
These aldehydes are effective in sterilization and disinfection processes.
319
What is the appearance and odor of **glutaraldehyde**?
A yellow liquid with a mild odor
## Footnote
Glutaraldehyde is known for its rapid and broad-spectrum antimicrobial activity.
320
How does **glutaraldehyde** disrupt cellular activity?
By cross-linking protein molecules on the cell surface
## Footnote
This process irreversibly disrupts the activity of enzymes and proteins within cells.
321
What is the classification of **glutaraldehyde**?
Sterilant and high-level disinfectant
## Footnote
It is effective against spores, fungi, and vegetative bacteria.
322
How long does it take for **glutaraldehyde** to kill spores?
3 hours
## Footnote
It is effective against fungi and vegetative bacteria in a few minutes.
323
What device is used to vaporize **glutaraldehyde** for sterilization?
Chemiclave
## Footnote
This device sterilizes delicate instruments without heat.
324
What are the advantages of **glutaraldehyde**?
* Retains potency in organic matter
* Noncorrosive
* Does not damage plastics
* Less toxic than formaldehyde
## Footnote
These properties make it suitable for sterilizing delicate medical instruments.
325
What is a principal disadvantage of **glutaraldehyde**?
Somewhat unstable with increased pH and temperature
## Footnote
This instability can affect its effectiveness.
326
What is the appearance of **ortho-phthalaldehyde (OPA)**?
A pale blue liquid with a barely detectable odor
## Footnote
OPA is approved as a high-level disinfectant by the EPA.
327
How does the mechanism of action of **OPA** compare to **glutaraldehyde**?
Similar mechanism of action
## Footnote
Both are effective against vegetative bacteria, fungi, and viruses.
328
What are the disadvantages of **ortho-phthalaldehyde (OPA)**?
* Inability to reliably destroy spores
* Tendency to stain proteins
## Footnote
This includes staining proteins in human skin.
329
What is **formaldehyde** and how is it commonly found?
A sharp, irritating gas that dissolves in water to form formalin
## Footnote
Pure formalin is a 31% solution of formaldehyde gas in water.
330
How does **formaldehyde** exert its microbicidal effect?
By attaching to nucleic acids and functional groups of amino acids
## Footnote
This mechanism contributes to its effectiveness as a disinfectant.
331
What is the classification of **ethylene oxide (ETO)** in terms of toxicity?
Carcinogen
## Footnote
ETO is highly toxic and has irritating effects on skin and mucous membranes.
332
Name the **gaseous sterilants** mentioned in the text.
* Ethylene oxide (ETO)
* Propylene oxide
* Chlorine dioxide
## Footnote
These gases are used for sterilization and disinfection of various materials.
333
What is a key feature of **ethylene oxide (ETO)** that makes it a sporicide?
Strong alkylating agent
## Footnote
ETO reacts with DNA and proteins, blocking replication and enzymatic actions.
334
How long does **ethylene oxide (ETO)** typically require for sterilization?
90 minutes to 3 hours
## Footnote
ETO is slow-acting and requires specific conditions for effective sterilization.
335
True or false: **Chlorine dioxide** works in the same way as chlorine compounds.
FALSE
## Footnote
Chlorine dioxide is a strong alkylating agent and disrupts proteins, differing from chlorine compounds.
336
What applications does **chlorine dioxide** have?
* Treatment of drinking water
* Wastewater treatment
* Food-processing equipment
* Medical waste treatment
* Decontamination of rooms and large spaces
## Footnote
Chlorine dioxide is effective against a wide range of microorganisms.
337
What are **detergents** classified as?
Surfactants
## Footnote
Detergents are polar molecules that can disrupt cell membranes of sensitive microbes.
338
Which type of detergents are more effective: **anionic** or **cationic**?
Cationic detergents
## Footnote
Quaternary ammonium compounds (quats) are a type of cationic detergent with better microbicidal power.
339
What is a major drawback of **quaternary ammonium compounds (quats)**?
* Ineffective against tuberculosis bacterium
* Ineffective against hepatitis virus
* Ineffective against Pseudomonas
* Ineffective against spores
## Footnote
Quats require alkaline conditions and their activity is reduced in the presence of organic matter.
340
What are **soaps** primarily made from?
Fatty acids and sodium or potassium salts
## Footnote
Soaps are weak microbicides and primarily serve as cleansing agents.
341
What common hospital pathogen is resistant to **soap**?
Pseudomonas
## Footnote
Various species of Pseudomonas can grow abundantly in soap dishes.
342
What are **heavy metals** in the context of microbial control?
* Mercury
* Silver
* Gold
* Copper
* Arsenic
* Zinc
## Footnote
These elements have been used for microbial control over several centuries, but only mercury and silver remain significant as germicides.
343
Which two heavy metals still have significant use as **germicides**?
* Mercury
* Silver
## Footnote
Other metals like zinc and iron are needed for biological functions but are not primarily used as germicides.
344
True or false: **Gold**, **copper**, and **arsenic** are still significant as germicides.
FALSE
## Footnote
Only mercury and silver are currently significant in microbial control.
345
Fill in the blank: **Heavy metals** are often referred to as such because of their relatively high _______.
atomic weights
## Footnote
This classification is based on the physical properties of these elements.
346
What are **heavy metals** in the context of microbial control?
* Mercury
* Silver
* Gold
* Copper
* Arsenic
* Zinc
## Footnote
These elements have been used for microbial control over several centuries, but only mercury and silver remain significant as germicides.
347
Which two heavy metals still have significant use as **germicides**?
* Mercury
* Silver
## Footnote
Other metals like zinc and iron are needed for biological functions but are not primarily used as germicides.
348
True or false: **Gold**, **copper**, and **arsenic** are still significant as germicides.
FALSE
## Footnote
Only mercury and silver are currently significant in microbial control.
349
Fill in the blank: **Heavy metals** are often referred to as such because of their relatively high _______.
atomic weights
## Footnote
This classification is based on the physical properties of these elements.
Microbiology
flashcards
Decks in class (36)
# Cards
-
Chemistry & Biochemistry49
-
Ch 8 Metabolic109
-
Ch. 13 Microbes131
-
Ch, 4 Prokaryotes54
-
Midterm Prep214
-
Ch 189
-
Ch. 2104
-
Ch. 489
-
Practice Test140
-
Scientific Disease Names10
-
Euk Vs Prok167
-
DNA Rep27
-
Lab Practicum19
-
Ch. 5 Eukaryotes245
-
Ch. 6147
-
Ch. 9386
-
Test 2 Review132
-
#11-51 Cards31
-
Ch. 7285
-
Ch. 11349
-
Ch. 12415
-
Extra 12450
-
Lab Review128
-
Lec 3 Review64
-
Ch 1456
-
Disease Cards 21-28, 52-6825
-
Disease Card Quiz177
-
Ch. 15315
-
Ch. 16319
-
Final Study Guide174
-
#10-20137
-
#21-31169
-
#32-43155
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#44-54160
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#55-68211
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Ch 1748
