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Biology 15 - General Microbiology > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

What does sepsis refer to in microbiology?

A

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

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2
Q

What does asepsis refer to in microbiology?

A

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

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3
Q

What is the purpose of aseptic surgery techniques?

A

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

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4
Q

Name three practices for controlling microbial growth.

A
  1. sterilization
  2. disinfection
  3. biocide/germacide
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5
Q

What is the difference between disinfection and sterilization?

A

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.

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6
Q

What is sterilization in microbiology?

A

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

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7
Q

What is disinfection in microbiology?

A

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

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8
Q

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

A

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

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9
Q

What is antisepsis, and where is it commonly used?

A

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

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10
Q

Explain the concepts of degerming and sanitization in microbiology.

A
  • 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.
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11
Q

What are biocides (germicides) in microbiology?

A

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

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12
Q

What is the purpose of a fungicide in microbiology?

A

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

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13
Q

Define a virucide in microbiology.

A

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

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14
Q

What is bacteriostasis, and how does it work?

A

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.

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15
Q

How do agents affect microbial membranes?

A

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

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16
Q

What happens when microbial proteins are damaged?

A

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

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17
Q

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

A
  • 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.
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18
Q

Factors that affect microbial death rates

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

A

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

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19
Q

Factors that affect microbial death rates

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

A

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.

20
Q

Factors that affect microbial death rates

What are the four factors affecting microbial death rates?

A
  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)
21
Q

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

A

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

22
Q

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?

A

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

23
Q

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

A

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

24
Q

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

A
  • Boiling
  • Autoclaving
  • Pasteurization
25
Q

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

A

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.

26
Q

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

A

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.

27
Q

How is the decimal reduction time (DRT) defined?

A

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.

28
Q

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

A

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.

29
Q

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

A

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

30
Q

What are the key characteristics of autoclave sterilization?

A

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.

31
Q

What is pasteurization, and what products are commonly pasteurized?

A

Pasteurization mildly heats products to kill microbes while preserving taste. Phosphatase test verifies pasteurization.

Used for milk, beer, yogurt. They each take a different amount of time to be pasteruized.

32
Q

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

A

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

33
Q

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

A

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.

34
Q

Radiation used to kill microbes

How does ionizing radiation work for microbial control, and what types are commonly used?

A

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

35
Q

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

A

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

36
Q

How do microwaves impact microbial control?

A

Microwaves primarily kill microbes through heat rather than direct antimicrobial action.

Not as effective as ionizing and nonionzing radiation.

37
Q

Which physical methods of controlling microbes are bacteriostatic?

A
  • Low temp: Refrigeration (0-7 celsius)
  • Heavy metals: Mercury
  • Aldehydes: Glutaraldehyde when used in a 2% solution
38
Q

How does osmotic pressure control growth of microbes?

A
  • Hypertonic solution: Cell goes through plasmolysis (water leaves cell)
  • Hypotonic solution: Cell gets lyzed (water rushes into cell and it bursts)
39
Q

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

A
  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
  5. Surfractants: Decrease surface tension among molecules of a liquid
  6. Oxidizing Agents: Oxidization
  7. Aldehydes: Inactivates proteins by forming covalent cross links with organic groups

Iodine is the oldest and most effective antiseptic.

40
Q

What are examples of alcohols that destroy microbes?

A
  • Ethanol
  • Isopropanol

AKA Purell and GermX

41
Q

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

A

Cresols: Triclosan (Bisphenol)

42
Q

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

A
  • When we use soap we must mechanically remove microbes through scrubbing.
  • Emulsification is also used (breaking oily film into tiny drops)
43
Q

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

A

Mouthwash

44
Q

What are examples of Halogens?

A
  • Iodine (Ex. Potatble Aqua pills)
  • Chlorine

Chlorine aka Sodium hypochlorite (Ex. Clorox)

45
Q

What are examples of heavy metals that can destroy microbes?

A
  • Silver
  • Copper
  • Zinc
46
Q

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

A
  1. Oxidizing agent: Peracetic Acid
  2. Aldehyde: Glutaraledehyde
47
Q

Mircobial death curve

What is the most resistant microbe? What is the least resistant microbe?

A

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

Biology 15 - General Microbiology (29 decks)

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