Unit 6 Objectives NOT DONE

Question 1

Define Sterilization, sterilant and give a typical example

Answer 1

Sterilization, Sterilant

Definition: Sterilization is the process of destroying or removing all forms of microbial life, including spores.

Example of Sterilant: Autoclaving or using chemicals like ethylene oxide gas.

Question 2

Define Aseptic and give a typical example

Answer 2

Aseptic

Definition: Aseptic techniques are procedures or practices that prevent contamination by pathogens.

Example: Using sterile gloves and disinfected equipment in surgery.

Question 3

Define Disinfectant, disinfection and give a typical example

Answer 3

Disinfectant, Disinfection

Definition: Disinfection is the process of eliminating or reducing harmful microorganisms on surfaces, but not necessarily spores.

Example of Disinfectant: Bleach solution used on countertops.

Question 4

Define Antisepsis, antiseptic and give a typical example

Answer 4

Antisepsis, Antiseptic

Definition: Antisepsis is the application of an antiseptic to living tissues to prevent infection by killing or inhibiting pathogens.

Example of Antiseptic: Hydrogen peroxide used to clean a wound.

Question 5

Define Degerming and give a typical example

Answer 5

Degerming

Definition: Degerming is the mechanical removal of microbes from a surface, such as skin, without necessarily killing them.

Example: Washing hands with soap.

Question 6

Define Sanitization and give a typical example

Answer 6

Sanitization

Definition: Sanitization reduces the number of pathogens to a safe level as judged by public health standards.

Example: Sanitizing dishes in a restaurant with hot water and detergent.

Question 7

Define –cidal vs –stasis and give a typical example of each

Answer 7

-cidal vs. -static

Definition:
“-cidal” refers to agents that kill microbes (e.g., bactericidal)

while “-static” refers to agents that inhibit microbial growth without necessarily killing them (e.g., bacteriostatic).

Example:
Bactericidal antibiotics (e.g., penicillin) kill bacteria,

while bacteriostatic antibiotics (e.g., tetracycline) inhibit bacterial growth.

Question 8

Given a specific location such as household bathroom or hospital surgical room, what appropriate control methods would you choose to appropriately “clean” it.

Answer 8

Household Bathroom:

• Disinfection: Use disinfectants like bleach or commercial bathroom cleaners to sanitize high-touch surfaces (toilets, sinks, faucets) and reduce microbial load.
• Degerming: Regularly wash surfaces with soap and water to mechanically remove dirt and microbes.
• Ventilation: Keep the bathroom well-ventilated to reduce mold growth and moisture buildup.

Question 9

Given a specific location such as household bathroom or hospital surgical room, what appropriate control methods would you choose to appropriately “clean” it.

Answer 9

Hospital Surgical Room:

• Sterilization: Use autoclaves to sterilize surgical instruments and equipment, ensuring the elimination of all microbial life, including spores.
• Aseptic Technique: Use aseptic methods, including sterilized gloves, gowns, and masks, to prevent contamination.
• Surface Disinfection: Regularly disinfect surfaces with hospital-grade disinfectants (e.g., quaternary ammonium compounds) before and after each procedure.
• Air Filtration: Use HEPA filters to maintain sterile air quality and minimize airborne contaminants.

Question 10

What environmental factors affect how a specific antimicrobial agent works?

Answer 10

1. Temperature:
   Higher temperatures: generally increase the activity of antimicrobial agents; speed up chemical reactions
   Lower temperatures: reduce their effectiveness.
2. pH: Some antimicrobials work best within specific pH ranges;
   Alkaline: bleach is more effective in alkaline conditions
   Acidic: other agents like acids work better in acidic environments.
3. Presence of Organic Matter: Organic materials (e.g., blood, tissue, dirt) can interfere with antimicrobials by binding to the agent or shielding microbes, reducing effectiveness.
4. Concentration of the Agent:
   Higher concentrations: typically enhance antimicrobial activity; this varies based on the agent and can also increase toxicity.
5. Contact Time: The longer an antimicrobial is in contact with microbes, the more effective it is at killing or inhibiting them.
6. Type of Microorganism: Different microbes (e.g., spores, viruses, Gram-positive vs. Gram-negative bacteria) have varying levels of resistance to antimicrobials, affecting how well the agent works.
7. Moisture: Water can facilitate the action of many antimicrobials, but some agents, such as alcohol, are less effective on wet surfaces due to dilution.

Question 11

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?
a. Autoclave

Answer 11

Autoclave

Target Site: Destroys microbes by applying steam heat and high pressure to denature proteins and disrupt cell structures.

Advantages: Highly effective at sterilizing, including killing spores; widely used in hospitals and labs.

Disadvantages: Requires high temperatures and pressure, which may damage heat-sensitive items.

Ideal Use: Sterilizing surgical tools, lab equipment, and media.

Question 12

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

b. Pasteurization

Answer 12

Pasteurization

Target Site: Kills pathogens by using moderate heat to damage microbial proteins and cell membranes.

Advantages: Reduces pathogens without significantly affecting food quality.

Disadvantages: Not a complete sterilization; some spoilage organisms may survive.

Ideal Use: Treating milk, juice, and other perishable food items.

Question 13

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

c. Ultrahigh-temperature sterilization (UHT)

Answer 13

Ultrahigh-Temperature (UHT) Sterilization

Target Site: Uses very high temperatures to denature microbial proteins.

Advantages: Extends shelf life of products without refrigeration; sterilizes effectively.

Disadvantages: Can alter taste or nutritional value in some foods.

Ideal Use: Long-term storage of dairy products like milk and creamers.

Question 14

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

d. Dry heat

Answer 14

Dry Heat

Target Site: Kills microbes by oxidizing cellular components.

Advantages: Useful for sterilizing powders, oils, and glassware.

Disadvantages: Requires higher temperatures and longer times than moist heat.

Ideal Use: Sterilizing items that cannot be steamed, such as metal instruments.

Question 15

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

e. Refrigeration & freezing

Answer 15

Refrigeration & Freezing

Target Site: Slows microbial metabolism and growth by reducing enzyme activity.

Advantages: Preserves food and medical supplies without chemical additives.

Disadvantages: Does not kill most microbes, just inhibits growth.

Ideal Use: Preserving perishable foods and biological samples.

Question 16

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

f. Dessication

Answer 16

Desiccation

Target Site: Removes water to halt microbial metabolism and reproduction.

Advantages: Simple and inexpensive; extends shelf life.

Disadvantages: Some microbes (e.g., spores) can survive desiccation.

Ideal Use: Storing grains, dried fruits, and some medications.

Question 17

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

g. Filtration

Answer 17

Filtration

Target Site: Physically removes microbes from liquids or air by passing them through a filter.

Advantages: Useful for heat-sensitive liquids and air purification.

Disadvantages: Does not remove all viruses or toxins.

Ideal Use: Sterilizing vaccines, medications, and cleanroom air.

Question 18

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

h. Osmotic pressure

Answer 18

Osmotic Pressure

Target Site: Uses high salt or sugar concentrations to draw water out of microbes, leading to dehydration.

Advantages: Inhibits microbial growth in foods.

Disadvantages: Ineffective against some molds and osmotolerant bacteria.

Ideal Use: Preserving foods like jams, salted meats, and pickles.

Question 19

What do the following physical means of microbial control target site? What is/are the advantage(s) and disadvantage(s) of each? Given a specific situation, what physical means of control would you choose?

i. Radiation (ionizing & nonionizing)

Answer 19

Radiation (Ionizing & Nonionizing)

Target Site:
Ionizing (X-rays, gamma rays) damages DNA;
nonionizing (UV light) causes DNA mutations.

Advantages: Effective at sterilizing, including killing spores (ionizing); UV used for surface disinfection.

Disadvantages: Requires safety precautions; UV limited to surfaces only.

Ideal Use: Sterilizing medical equipment, pharmaceuticals, and surfaces in hospitals.

Question 20

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

a. Phenolics

Answer 20

Phenolics

Target Site: Disrupt cell membranes and denature proteins.

Pros: Effective on surfaces, stable, and works well in the presence of organic material.

Cons: Can be toxic and irritating to skin; some phenolics have strong odors.

Example: Lysol (contains phenolic compounds like o-phenylphenol).

Ideal Use: Disinfecting surfaces in healthcare settings.

Why Not a Sterilant?: Phenolics are generally effective against many pathogens but may not reliably kill spores.

Question 21

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

b. Alcohol

Answer 21

Alcohol

Target Site: Denatures proteins and disrupts cell membranes.

Pros: Fast-acting and effective against many bacteria and viruses.

Cons: Flammable and evaporates quickly, reducing contact time; ineffective on spores.

Example: Isopropyl alcohol (rubbing alcohol).

Ideal Use: Skin antiseptic or disinfecting small instruments.

Why Not a Sterilant?: Alcohol does not kill all spores and may not achieve complete sterilization.

Question 22

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

c. Halogens

Answer 22

Halogens

Target Site: Oxidize cellular components, especially proteins and nucleic acids.

Pros: Broad-spectrum antimicrobial, effective at low concentrations.

Cons: Can be corrosive and irritating; may lose potency in organic matter.

Example: Chlorine in bleach.

Ideal Use: Disinfecting water, surfaces, and equipment.

Why Not a Sterilant?: May not be effective against all spores at typical usage concentrations.

Question 23

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

d. Oxidizing agents

Answer 23

Oxidizing Agents

Target Site: Produce free radicals that damage cellular components.

Pros: Highly effective, even against spores, at higher concentrations.

Cons: Can be corrosive or damaging to tissues and materials.

Example: Hydrogen peroxide.

Ideal Use: Disinfecting surfaces, wounds, and medical devices.

Why Not a Sterilant?: While effective, high concentrations needed for sporicidal activity can be hazardous.

Question 24

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

e. Surfactants including “quats”

Answer 24

Surfactants, including “quats” (quaternary ammonium compounds)

Target Site: Disrupt cell membranes and remove dirt and oils.

Pros: Non-toxic, stable, and effective against many microbes.

Cons: Limited effectiveness on spores and some Gram-negative bacteria.

Example: Benzalkonium chloride (a quat).

Ideal Use: Disinfecting non-critical surfaces in households and hospitals.

Why Not a Sterilant?: Not effective against all pathogens, especially spores and non-enveloped viruses.

Question 25

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

f. Heavy metals

Answer 25

Heavy Metals

Target Site: Bind to and inactivate proteins, affecting enzyme function.

Pros: Long-lasting effect in certain applications; bacteriostatic properties.

Cons: Can be toxic to humans and the environment; limited use due to toxicity.

Example: Silver nitrate (used in wound care).

Ideal Use: Antiseptic in wound dressings and medical equipment coatings.

Why Not a Sterilant?: Heavy metals are mainly bacteriostatic and not always reliable in killing spores.

Question 26

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

g. Aldehydes

Answer 26

Aldehydes

Target Site: Crosslink proteins and nucleic acids, effectively denaturing them.

Pros: Highly effective against all microbes, including spores, at sufficient concentrations.

Cons: Toxic, irritating, and requires long exposure time; requires proper ventilation.

Example: Glutaraldehyde (used for sterilizing medical equipment).

Ideal Use: Sterilizing surgical instruments and sensitive medical devices.

Why Not a Sterilant?: Though effective, the toxicity and handling requirements make it less suitable for routine disinfection.

Question 27

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

h. Gases

Answer 27

Gases

Target Site: Penetrate materials and react with proteins and DNA.

Pros: Effective sterilant for heat-sensitive materials; penetrates hard-to-reach areas.

Cons: Toxic, requires special equipment, and slow process.

Example: Ethylene oxide (used in medical device sterilization).

Ideal Use: Sterilizing medical devices and equipment that cannot be autoclaved.

Why Not a Sterilant?: Gases like ethylene oxide are sterilants but are limited by safety and cost for widespread use.

Question 28

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

i. Enzymes

Answer 28

Enzymes

Target Site: Break down specific microbial components, such as cell walls or biofilms.

Pros: Highly specific and effective without being toxic; useful in medical applications.

Cons: Often target-specific; can be costly and may require controlled conditions.

Example: Lysozyme (breaks down bacterial cell walls).

Ideal Use: Disinfecting medical instruments or controlling specific microbial contaminants.

Why Not a Sterilant?: Enzymes are typically specific and may not kill all types of microbes or spores.

Question 29

5) What do the following chemical means of microbial control target site? What is/are the pros and cons of each? Know an example of each. Given a specific situation, what chemical means of control would you choose? Why aren’t the majority of chemical means of control labeled as “sterilants”?

Answer 29

Most chemical controls are not labeled as “sterilants” because more resistant microbes aren’t affected by chemicals
(endospores & prions);

Also toxicity as well as other limitations such as explosive or highly corrosive nature of chemicals have to be taken into consideration

Question 30

Define antimicrobial drug

Answer 30

Any compound used to treat infectious disease; may also function as intermediate-level disinfectant;

Chemotherapeutic agent used to treat microbial infection

Antimicrobial drugs include:
1. antibiotics
2. semisynthetics
3. synthetics

Question 31

Define antibiotic

Answer 31

A type of antimicrobial drug that is naturally produced by microorganisms (like bacteria or fungi) to kill or inhibit other microorganisms, particularly bacteria.

Question 32

What is it called when scientists chemically modify an antibiotic?

Answer 32

The agent is called a semisynthetic

Question 33

Define synthetic drug

Answer 33

A drug that is completely manufactured in a laboratory, rather than derived from natural sources, designed to treat infections or diseases.

Question 34

Define chemotherapeutic index

Answer 34

A drug’s therapeutic index (TI) is essentially a ratio of the drug’s tolerated dose to its effective dose. The higher the TI, the safer the drug.

Question 35

What are Chemotherapeutic agents?

Answer 35

Chemotherapeutic agents are chemicals used to treat diseases.

Among them are antimicrobial agents or antimicrobials these include:
1. antibiotics (biologically produced agents)
2. semisynthetic antimicrobials (chemically modified antibiotics)
2. synthetic drugs

Question 36

Define semi-synthetic drug

Answer 36

A drug that is chemically modified from a naturally occurring antibiotic to enhance its efficacy, spectrum, or stability.

Question 37

Define selective toxicity

Answer 37

Principle by which an effective antimicrobial agent must be more toxic to a pathogen than to the pathogen’s host

Question 38

What general features would the “ideal” antimicrobial drug have?

Answer 38

• Readily available
• Inexpensive
• Chemically stable (so that it can be transported easily and stored for long periods of time)
• Easily administered
• Nontoxic and nonallergenic
• Selectively toxic against a wide range of pathogens

Question 39

What factors must a doctor consider when choosing an antimicrobial drug?

Answer 39

Doctors and medical laboratory scientists must evaluate antimicrobials with respect to several characteristics:

• The types of pathogens against which they are effective
• Their effectiveness, including the dosages required to be effective
• The routes by which they can be administered
• Their overall safety and any side effects they produce

Question 40

What are the general targets sites for an Antibacterial drug
Antiviral drug
Anti-fungal drug

Answer 40

Antibacterial:
- Inhibit CW synthesis
- Inhibit proteins synthesis or activate proteins
- Disrupt lipids (CM)
- Inhibit metabolic pathway
- Inhibit nucleic acid synthesis

Antiviral:
- Inhibit proteins synthesis or activate proteins
- Disrupt lipids (envelope)
- Inhibit nucleic acid synthesis
- Entry & uncoating

Anti-fungal:
- Inhibit CW synthesis
- Inhibit metabolic pathway
- Inhibit nucleic acid synthesis

Question 41

Comparing the three types of drugs, are there any similarities in target sites?

Antibacterial drug
Antiviral drug
Anti-fungal drug

Answer 41

All 3: Inhibit nucleic acid synthesis

Bacterial and viral:
- Inhibit proteins synthesis or activate proteins
- Disrupt lipids (CM/envelope)

Bacteria and fungal:
- Inhibit CW synthesis
- Inhibit metabolic pathway

Question 42

Explain why there may be a difference or similarity in target sites of
Antibacterial drug
Antiviral drug
Anti-fungal drug

In other words, why would it be more difficult to find an antiviral drug, an anti-fungal drug and/or a drug against a protozoan vs an antibacterial drug?

Answer 42

Because viruses rely on host cell machinery to replicate, so targeting the virus without harming host cells is difficult.

Similarly, fungi and protozoa are eukaryotic, like human cells, meaning they share more cellular structures with us than bacteria do, which limits selective target options and increases the risk of host toxicity

Question 43

What does antimicrobial resistance mean?

Answer 43

The ability of microbes to survive and grow despite the presence of drugs designed to inhibit or kill them

Question 44

Explain how antimicrobial resistance arises. In your answer address the following:
a. What mechanisms do these resistant microbe use so they avoid the effects of the drug?
b. Do bacteria acquire resistance genes? If so, explain how they acquire the resistance.
c. What strategies could we potentially or are using to control the spread of these resistant strains?

Answer 44

Resistance arises due to genetic changes in microbes, often accelerated by the overuse and misuse of antimicrobial drugs, which select for resistant strains.

Question 45

Explain how antimicrobial resistance arises. In your answer address the following:
a. What mechanisms do these resistant microbe use so they avoid the effects of the drug?
b. Do bacteria acquire resistance genes? If so, explain how they acquire the resistance.
c. What strategies could we potentially or are using to control the spread of these resistant strains?

Answer 45

a. Mechanisms of Resistance:
Resistant microbes use several mechanisms to evade drugs, including:

• Drug Inactivation: Producing enzymes that break down or modify the drug
• Efflux Pumps: Actively pumping the drug out of the cell before it can act.
• Target Modification: Altering the drug’s target site, so the drug no longer binds effectively (e.g., modifications in ribosomal proteins or enzymes).
• Metabolic Pathway Changes: Using alternative metabolic pathways to bypass the drug’s action.

Question 46

Explain how antimicrobial resistance arises. In your answer address the following:
a. What mechanisms do these resistant microbe use so they avoid the effects of the drug?
b. Do bacteria acquire resistance genes? If so, explain how they acquire the resistance.
c. What strategies could we potentially or are using to control the spread of these resistant strains?

Answer 46

b. Acquisition of Resistance Genes:
Yes, bacteria can acquire resistance genes through:

• Mutation: Spontaneous genetic mutations during DNA replication.
• Horizontal Gene Transfer: Transferring resistance genes between bacteria through processes like
• conjugation (transfer of plasmids),
• transformation (uptake of free DNA), or
• transduction (gene transfer by bacteriophages).

Question 47

Explain how antimicrobial resistance arises. In your answer address the following:
a. What mechanisms do these resistant microbe use so they avoid the effects of the drug?
b. Do bacteria acquire resistance genes? If so, explain how they acquire the resistance.
c. What strategies could we potentially or are using to control the spread of these resistant strains?

Answer 47

c. Strategies to Control Resistant Strains:

To control the spread of resistant strains, we can:

• Limit Use of Antibiotics: Using antibiotics only when necessary and avoiding overuse.
• Develop New Drugs and Drug Combinations: Creating drugs that target resistant mechanisms and using combination therapies to reduce resistance development.
• Implement Infection Control Measures: Enforcing hygiene and sanitation practices in healthcare and community settings.
• Encourage Vaccination: Reducing infections through vaccination to decrease the need for antibiotics.

Question 48

Describe the transformation experiment performed in lab & be able to analyze data of a similar type of experiment.

Answer 48

The transformation experiment typically involves introducing foreign DNA (such as a plasmid) into bacterial cells using competent bacteria;

The experiment usually involves mixing the plasmid with competent bacteria and applying a heat shock or other treatments to facilitate DNA uptake.

Afterward, the bacteria are plated on agar containing an antibiotic.

Only those bacteria that have successfully taken up the plasmid with the corresponding antibiotic resistance gene will grow and form colonies.

Question 49

Be able to figure out what may have gone wrong with the transformation experiment given a specific result.

Answer 49

Transformation Experiment:

Analyzing Data:
If transformation was successful, colonies will grow on the selective plate, but not on the non-selective plate.
If no colonies appear on the selective plate, it may indicate failure in transformation, issues with the plasmid, or bacterial competence.

Possible Problems in the Experiment:

Inadequate Heat Shock: bacteria may not take up the plasmid. No growth on selective plates would indicate this.

Plasmid Issues: If the plasmid used is defective or does not contain the correct antibiotic resistance gene, no colonies will form on the selective plate.

Improper Media or Antibiotic Concentration: If the agar media or antibiotic concentration is incorrect, it could prevent proper selection, leading to inaccurate results.

Question 50

Define “competent” with respect to the transformation experiment;

How can cells become “competent”

Answer 50

Bacteria that are able to take up foreign DNA from their environment;

How Cells Become Competent:
Chemical Treatment: chemicals such as calcium chloride, temporarily makes the cell membrane permeable to DNA.

Electroporation: An electric field is applied to create temporary pores in the bacterial cell membrane, allowing DNA uptake.

Natural Competence: Some bacteria naturally undergo competence during certain growth phases

Question 51

In exercise 17, we performed an epidemiological experiment. Given specific data of a similar experiment, explain your analysis of the results. Why is it potentially impossible to identify patient zero? What factors may impede identifying patient zero in a real life scenario? Compare & contrast our experiment vs. a real life situation.