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BIO150 > Chapter 7 > Flashcards

Chapter 7 Flashcards

1
Q

Sepsis

A

Bacterial contamination

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2
Q

Asepsis

A

The absence of significant contamination Aseptic surgery techniques prevent the microbial contamination of wounds

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3
Q

Sterilization

A

Removing and destroying all microbial life

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4
Q

Disinfection

A

Destroying harmful microorganisms

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5
Q

Sanitization

A

Lowering microbial counts on eating utensils to save levels

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6
Q

Biocide

A

(Germicide) Treatments that kill microbes

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7
Q

Bacteriostasis

A

Inhibiting, not killing, microbes

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8
Q

Effectiveness of treatment depends on:

A
  • Number of microbes
  • Environment (organic matter, temperature, biofilms)
  • Time of exposure
  • Microbial characteristics
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9
Q

Actions of Microbial Control Agents

A
  • Alteration of membrane permeability
  • Damage to proteins (enzymes)
  • Damage to nucleic acids
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10
Q

Physical method of sterilization

Chemical method of sterilization

A

Apply heat, radiation

Chemicals, disinfectants

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11
Q

To kill endospores

A

You need to apply temperatures higher than 100º C and pressure

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12
Q

Moist Heat Sterilization

A
  • Autoclave: steam under pressure
  • 121 ºC at 15 psi for 15 min
  • Kills all microorganisms and endospores
  • Steam must contact the item’s surface
  • Large containers require longer sterilization times
  • Test strips are used to indicate sterility
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13
Q

Dry Heat Sterilization

A
  • Kills by oxidation
    • Flaming (wire loop)
    • Hot-air oven (powders, sharp instruments)
    • 170º C for 2 hrs
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14
Q

Filtration

A
  • Passage of substance through a screenlike material
  • Used for heat-sensitive materials
  • High-efficiency particulate air (HEPA) filters remove microbes >0.3µm
  • Membrane filters removes microbes >0.22 µm
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15
Q

Physical Methods of Microbial Control

A
  • Low temperature has a bacteriostatic effect
  • Desiccation
  • Osmotic pressure
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16
Q

Example of osmotic pressure for microbial control

A

Osmotic pressure uses salts and sugars to create hypertonic environment; causes plasmolysis

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17
Q

Dessication

A

Absence of water which prevents metabolism (microbial growth)

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18
Q

Examples of low temperature bacteriostatic effect methods

A
  • Refrigeration
  • Deep-freezing
  • Lyphilization (freeze drying)
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19
Q

Name 3 methods of microbial control through radiation

A
  • Ionizing radiation
  • Nonionizing radiation (UV, 260 nm)
  • Microwaves
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20
Q

Ionizing radiation

A
  • X-rays, gamma rays, electron beams
    • Ionizes water to create reactive hydroxyl radicals
    • Damages DNA by causing lethal mutations
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21
Q

Nonionizing radiation

A

Damages DNA by creating thymine dimers

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22
Q

Microwaves

A

Kill by heat; not especially antimicrobial

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23
Q

Principles of Effective Disinfection

A
  • Concentration of disinfectant
  • Organic Matter
  • pH
  • Time
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24
Q

The Disk-Diffusion Method

A
  • Evaluates efficacy of chemica agents
  • Filter paper disks are soaked in a chemical and placed on a culture
  • Look for zone of inhibition around disks
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25
Q

Phenol and Phenolics

A
  • Injures lipids of plasma membranes, causing leakage
  • E.g. mycobacteria contains lipis. Phenols are used to disinfect pus, saliva, and feces.
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26
Q

Biguanides

A
  • Chlorhexidine
  • Used in surgical hand scrubs
  • Disrupt plasma membranes
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27
Q

Name two halogens

A
  • Iodine
  • Chlorine
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28
Q

Iodine (name 2 examples and function)

A

(Halogen)

  • Tincture: solution in aqueous alcohol
  • Iodophor: combined with organic molecules
  • Impairs protein synthesis
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29
Q

Chlorine

A
  • Oxidizing agents: shut down cellular enzyme systems
  • Bleach: hypochlorous acid (HOCl)
  • Chloramine: chlorine + ammonia
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30
Q

Alcohols

A
  • Denature proteins and dissolve lipids
  • No effect on endospores and nonenveloped viruses
  • Ethanol and isoporpanol
    • Require water
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31
Q

Oligodynamic action

A

Very small amounts exert antimicrobial activity

32
Q

What percentage concentration of alcohol do you use in the lab?

A

60-70%

33
Q

Heavy Metals and Their Compounds

A
  • Oligodynamic action - very small amounts exert antimicrobial activity
  • Acts on the sulfhydryl groups and denature proteins
  • Ag, Hg, Cu, Zn
    • Silver nitrate is used to prevent ophthalmia neonatorum
    • Mercuric chloride prevents mildew in paint
    • Copper Sulfate is an algicide
    • Zinc chloride is found in mouthwash
34
Q

Chemical Food Preservatives

A
  • Sulfur dioxide prevents wine spoilage
  • Nitrites and nitrates prevent endospore germination
35
Q

Chemical Sterilization

A
  • Cross-links nucleic acids and proteins
  • Used for heat-sensitive material
    • Ehtylene oxide
    • Sterilization of disposable health care products
36
Q

How does an autoclave sterilize bacteria?

A

By moist hear sterilization. This denaturizes the proteins. Uses 121°C and 15 lbs of pressure for 15 min. Does not work on heat sensitive microbes.

37
Q

How does an oven kill bacteria?

A

Uses dry heat for sterilization. Requires temperature of 170°C for 2 hours. Also what flaming the wireloop involves.

38
Q

How do filters kill microbes? How many types of filters are there?

A

Filters can sterilize heat sensitive materials such as enzymes and culture media, vaccines and antibiotics. Two types of filters:

  1. High-efficiency air (HEPA) filters - can remove microbes >.0.3µm (for air)
  2. Membrane filters: remove microbes >0.22µm
39
Q

Which tool is used to kill bacteria with radiation?

A

X-rays. This is ionizing radiation which creates free radicals in the cell bu ionizing water to create reactive hydroxyl radicals.

Low levels of ionizing radiation are used to preserve spices, meats, and vegetables. Also used for the sterilization of medical equipmentsuch as syringes, surgical gloves.

40
Q

Whihc type of radiation is used to damage the DNA of microbes? Where is it used and what is its disadvantage?

A

UV light;

Cafeterias, operating rooms, hospital rooms

It does not penetrate very well

41
Q

Which sterilization method alters the cell membrane?

A

Iodine

42
Q

Which sterilization method prevents the functioning of cellular enzymes?

A

Chlorine

43
Q

Which sterilization method acts on lipid containing cellular components?

A

Phenol

44
Q

Which sterilization methods acts on sulfhydryl groups of cellular proteins?

A

Heavy metals. Cu, Ag, Hg, Zn

45
Q

Which of the following does not kill endospores?

Autoclave

Incineration

Pasteurization

Hot air sterilization

A

Pasteurization

46
Q

Which of the following is most likely to be bactericidal?

Membrane filtration

Deep freezing

Lyophilization

Ionizing radiation

A

Ionizing radiation

47
Q

What is antibiotic resistance and what measures can be taken to minimize the drug resistance?

A

It is when bacterias are no longer susceptible to antibiotics. Common causes of this are using outdated antibiotics, using them on innapropriate diseases(i.e. common cold), not using the medication correctly or completely, using someone else’s leftover antibiotics.

48
Q

What is botulism?

A

Food poisoning caused by a bacterium (botulinum) growing on improperly sterilized canned meats and other preserved foods.

49
Q

Why were nitrates and nitrites used in food preservation? Are they safe?

A

Because many people used to die of botulism from canned food. It is also used to preserve meats and the color in meat.

Nitrites and Nitrates are not entirely safe because they have cancer causing agents. FDA mandates the minimization of use of nitrates and nitrites in foods. Meat makes its own nitrates and nitrites

50
Q

What are some examples of chemical methods for sterilization?

A

Halogens, Alcohols, Phenols, Sulfur dioxide, Ethylene oxide.

51
Q

Which chemical sterilization techniques prevents endospore germination?

A

Use of nitrites and nitrates

52
Q

Which chemical sterilization method is a gas and can be used on heat sensitive materials?

A

Ethylene Oxide

53
Q

Which chemical sterilization technique acts on the phospholipid plasma membrane? How is it effective in this manner?

What is it used to disinfect?

A

Phenols; this causes leakage of the cellular contents.

Mycobacteria parce que they contain a lot of lipids in the cell wall; very good on treating pus, saliva, and feces.

54
Q

Which chemical technique is effective as an antiseptic? Which one alters the cell membrane and stop protein synthesis and which one stops enzymes from functioning by oxidation?

A

Halogens

Iodine, Chlorine

55
Q

How does iodine behave as an antiseptic?

A

Alters the cell membrane and stops protein synthesis

56
Q

How does chlorine behave as an antiseptic?

A

It stops enzyme activity by oxidation

57
Q

Which chemical method has no effect on endospores and non-enveloped viruses?

A

Alcohol

58
Q

Heavy metals have bactericidal activity. How does this work?

A

They combine with cellular protein and cause denaturization.

59
Q

What is chemotherapy?

A

The use of chemicals to treat a disease

60
Q

What is an antibiotic?

A

substance produced by a microbe that inhibits another microbe

61
Q

What are antimicrobial drugs?

A

synthetic substances that interfere with the growth of microbes

62
Q

Which genus is responsible for producing most of the natural antibiotics? Where is it found?

A

Steptomyces - bacteria found in soil

63
Q

How does penicillin work?

A

Prevents the synthesis of peptidoglycan

64
Q

Chloramphenicol, erythromycin, steptomycin and tetracycline affect….

A

bacterial 70S ribosomes(protein synthesis)

65
Q

What do antimicrobial peptides do?

A

Change membrane permeability

66
Q

What do anti-fungal drugs combine with?

A

The membrane sterol

67
Q

What do rifamycin and quinolones do?

A

Interfere with DNA replication and transcription

68
Q

What do sulfanilamides do?

A

They affect the synthesis of folic acid

69
Q

What are the two types of penicilins?

A
  1. Natural: extracted fro mpiniccilium cultures; narrow spectrum of activity
  2. Semisynthetic; contain chemically added side chains making them resistant to penicillinases
70
Q

What is used for the treatment of tuberculosis and leprosy?

A

Isoniazid and ethambutol

71
Q

How does chloramphenicol affect bacteria?

What does it suppress?

A

Inhibits peptide bond formation- binds to 50S subunit of the 70S ribosome

Synthesized chemically; broad spectruml can suppress bone marrow and affect blood formation?

72
Q

How do sulfanomides work?

A

Inhibit the folic acid synthesis needed for nucleic acid and protein synthesis

competitively bond to enzyme for PABA production (folic acid precursor)

73
Q

Synergism

A

the working together of two or more drugs, muscles, etc, to produce an effect greater than the sum of their individual effects.

74
Q

Super bugs

A

bacteria that are resistant to large numbers of antibiotics

75
Q

Resistant genes are often spread _______ among bacteria or plasmids via _______.

A

Horizontally; conjugation or transduction

76
Q

What are two examples of polypeptide antibiotics?

A

Bacitracin - topical application; works aginst gram-positives

Vancomycin: gylcopeptide; last line against antibiotic-resistant MRSA

BIO150 (15 decks)

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