Chapter 7

Question 1

What does sepsis refer to in microbiology?

Answer 1

In microbiology, sepsis refers to bacterial contamination. (Example: Septic Tank)

Question 2

What does asepsis refer to in microbiology?

Answer 2

Asepsis in microbiology refers to the absence of significant microbial contamination.

Question 3

What is the purpose of aseptic surgery techniques?

Answer 3

Aseptic surgery techniques are used to prevent microbial contamination of wounds and surgical sites.

Question 4

Name three practices for controlling microbial growth.

Answer 4

1. sterilization
2. disinfection
3. biocide/germacide

Question 5

What is the difference between disinfection and sterilization?

Answer 5

Disinfection involves reducing microbial activity to a level that is considered safe for public health. Sterilization, on the other hand, completely eliminates all forms of microbial life.

Question 6

What is sterilization in microbiology?

Answer 6

Sterilization refers to the complete removal and destruction of all microbial life.

Question 7

What is disinfection in microbiology?

Answer 7

Disinfection involves the process of destroying harmful microorganisms, typically on inanimate objects or surfaces.

Question 8

What is the purpose of commercial sterilization in the food industry?

Answer 8

Commercial sterilization is used to kill Clostridium botulinum endospores in canned goods to prevent foodborne illnesses.

Question 9

What is antisepsis, and where is it commonly used?

Answer 9

Antisepsis is the destruction of harmful microorganisms from living tissue. It is often used with antiseptics to disinfect wounds and living tissues.

Question 10

Explain the concepts of degerming and sanitization in microbiology.

Answer 10

• Degerming is the mechanical removal of microbes from a limited area, typically through cleaning.
• Sanitization involves reducing microbial counts on eating utensils to safe levels, ensuring they are safe for use.

Question 11

What are biocides (germicides) in microbiology?

Answer 11

Biocides, also known as germicides, are treatments that are designed to kill microbes.

Question 12

What is the purpose of a fungicide in microbiology?

Answer 12

A fungicide is used to kill fungi, preventing their growth and reproduction.

Question 13

Define a virucide in microbiology.

Answer 13

A virucide is a substance or treatment that inactivates or destroys viruses.

Question 14

What is bacteriostasis, and how does it work?

Answer 14

Bacteriostasis refers to the inhibition of the growth and multiplication of microbes. When a bacteriostatic agent is removed, microbial growth may resume.
One common application of bacteriostasis is in the manufacture of plastics.

Question 15

How do agents affect microbial membranes?

Answer 15

Agents can alter membrane permeability, leading to membrane leaks (lysis) and microbial death.

Question 16

What happens when microbial proteins are damaged?

Answer 16

Damaged proteins, often referred to as “little bags of enzymes,” denature due to factors like heat and chemicals, disrupting essential microbial processes.

Question 17

How do agents cause damage to microbial nucleic acids, and what are the consequences?

Answer 17

• Agents can damage nucleic acids through heat, chemicals, and UV radiation.
• Rendering microbes incapable of replication and protein synthesis, thereby inhibiting their growth and reproduction.

Question 18

Factors that affect microbial death rates

What is one factor that affects the death rate of microbes?

Answer 18

The number of microbes present. More microbes generally result in a longer time required for their death.

Question 19

Factors that affect microbial death rates

What are some environmental influences that can affect microbial death rates?

Answer 19

Environmental factors include:
1. The presence of organic matter
2. The presence of biofilms
3. The nature of the suspending medium (such as heat treatment), and temperature.

Question 20

Factors that affect microbial death rates

What are the four factors affecting microbial death rates?

Answer 20

1. Number of microbes (More microbes, longer it takes)
2. Environmental influences (Presence of organic matter, biofilms)
3. Time of exposure
4. Characteristics of microbe (antibiotic resistance)

Question 21

How does the time of exposure impact the effectiveness of chemical antimicrobials?

Answer 21

Chemical antimicrobials often require extended exposure time to effectively kill microbes.

Question 22

What is another factor that influences the death rate of microbes?

Think of special characteristics of bacteria: Does it have resistance against antibiotics? Does it produce toxins?

Answer 22

The characteristics of the microbe itself can also impact its susceptibility to antimicrobial treatments

Question 23

What are some environmental factors that affect the growth of microorganisms?

Answer 23

Environmental factors include:
1. Heat (both dry and moist heat)
2. boiling
3. autoclaving
4. pasteurization, filtration
5. low temperature
6. radiation (both nonionizing and ionizing)
7. osmotic pressure

Question 24

Moist heat is used to kill microorganisms. What are examples of moist heat and the procedures used to kill them?

Answer 24

• Boiling
• Autoclaving
• Pasteurization

Question 25

What is the thermal death point (TDP), and what does it indicate?

Answer 25

The thermal death point (TDP) is the lowest temperature at which all microbes in a particular liquid suspension will be killed in 10 minutes. It indicates the minimum temperature required for complete microbial destruction.

Question 26

What is the thermal death time (TDT), and what does it represent?

Answer 26

The thermal death time (TDT) is the minimal length of time required for all microbes in a liquid culture to be killed at a given temperature. It indicates the time needed for microbial sterilization at that specific temperature.

Question 27

How is the decimal reduction time (DRT) defined?

Answer 27

The decimal reduction time (DRT) is the time, in minutes, in which 90% of a population of bacteria at a given temperature will be killed. It measures the effectiveness of heat treatment in reducing microbial numbers.

Question 28

How does dry heat primarily kill microbes, and what are some methods of dry heat sterilization?

Answer 28

Dry heat kills microbes through oxidation effects. Methods of dry heat sterilization include direct flaming, hot air sterilization (items placed in an oven), and maintaining 170°C for 2 hours to ensure sterilization.

Question 29

How does moist heat sterilization work, and what are some common methods?

Answer 29

Moist heat coagulates proteins. Methods include free-flowing steam, autoclave (121°C, 15 psi, 15 min), boiling, and pasteurization.

Question 30

What are the key characteristics of autoclave sterilization?

Answer 30

Autoclave sterilization uses steam under pressure at 121°C, 15 psi, for 15 minutes. Effective when steam contacts the item directly or in a small aqueous solution.

Question 31

What is pasteurization, and what products are commonly pasteurized?

Answer 31

Pasteurization mildly heats products to kill microbes while preserving taste. Phosphatase test verifies pasteurization. ## Footnote Used for milk, beer, yogurt. They each take a different amount of time to be pasteruized.

Question 32

What is filtration in microbiology, and what can it remove?

Answer 32

Filtration passes substances through a screen-like material. It removes microbes of various sizes, with some filters as small as 0.01 μm capable of filtering out viruses and large proteins. | CAN NOT remove flexible bacteria (spirochetes) & wall-less mycoplasma

Question 33

What are some low-temperature microbial control methods, and how do they work?

Answer 33

Low-temperature methods include: * Refrigeration (0-7°C) these put the bacteria in a bacteriostatic effect * Fast freezing in deep freezers * Slow freezing in regular freezers. Slow freezing can harm microbes by disrupting their cellular and molecular structure.

Question 34

# Radiation used to kill microbes How does ionizing radiation work for microbial control, and what types are commonly used?

Answer 34

Ionizing radiation (e.g., X-rays, gamma rays, electron beams) ionizes water to create reactive hydroxyl radicals, damaging microbial DNA through lethal mutations.

Question 35

What is nonionizing radiation, and how does it affect microbial control?

Answer 35

Nonionizing radiation (e.g., ultraviolet) damages microbial DNA by creating thymine dimers, making it effective for microbial control.

Question 36

How do microwaves impact microbial control?

Answer 36

Microwaves primarily kill microbes through heat rather than direct antimicrobial action. | Not as effective as ionizing and nonionzing radiation.

Question 37

Which physical methods of controlling microbes are bacteriostatic?

Answer 37

* Low temp: Refrigeration (0-7 celsius) * Heavy metals: Mercury * Aldehydes: Glutaraldehyde when used in a 2% solution

Question 38

How does osmotic pressure control growth of microbes?

Answer 38

* Hypertonic solution: Cell goes through plasmolysis (water leaves cell) * Hypotonic solution: Cell gets lyzed (water rushes into cell and it bursts)

Question 39

There are 8 chemical methods of microbial control, each of them as a mode of action. What are they?

Answer 39

1. **Alcohols**: Usually denatures protein. Can also disrupt membranes and dissolve many lipids 2. **Phenols & Phenolics**: Injure lipids of plasma membranes causing leakage 3. **Heavy metals**: Denature proteins 4. **Biguandies**: Disrupt plamsa membranes (especially gram-positive bacteria) 5A. **Halogens-Iodine**: Impairs protein synthesis and alters cell membranes 5B. **Halogens-Chlorine**: Prevents cellular enzyme system from functioning 6. **Surfractants**: Decrease surface tension among molecules of a liquid 7. **Oxidizing Agents**: Oxidization 8. **Aldehydes**: Inactivates proteins by forming covalent cross links with organic groups ## Footnote Iodine is the oldest and most effective antiseptic.

Question 40

What are examples of alcohols that destroy microbes?

Answer 40

* Ethanol * Isopropanol | AKA Purell and GermX

Question 41

Phenols and Phenolics are in the brand **Lysol**. What is the main ingredient in Lysol?

Answer 41

Cresols: Triclosan (Bisphenol)

Question 42

Surfractants are in soap and detergents. How are surfractants used to destroy microbes on the human body?

Answer 42

* When we use soap we must mechanically remove microbes through scrubbing. * Emulsification is also used (breaking oily film into tiny drops)

Question 43

What is the only example of Biguanides that was shared in class?

Answer 43

Mouthwash

Question 44

What are examples of Halogens?

Answer 44

* Iodine (Ex. Potatble Aqua pills) * Chlorine | Chlorine aka Sodium hypochlorite (Ex. Clorox)

Question 45

What are examples of heavy metals that can destroy microbes?

Answer 45

* Silver * Copper * Zinc

Question 46

There are two chemicals that act as sterilants, what are they?

Answer 46

1. Oxidizing agent: Peracetic Acid 2. Aldehyde: Glutaraledehyde

Question 47

# Mircobial death curve What is the most resistant microbe? What is the least resistant microbe?

Answer 47

Most resistant = Prions and Endospores Least resistant = Gram-positive bacteria and Virsues with lipid envelopes