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Microbiology > Chp 7 > Flashcards

Chp 7 Flashcards

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Biology 101 flashcards
1
Q

Sepsis

A

refers to bacterial contamination

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2
Q

Asepsis

A

is the absence of significant contamination

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3
Q

Aseptic surgery techniques prevent

A

the microbial contamination of wounds

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4
Q

Sterilization

A

removing and destroying all microbial life

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5
Q

Commercial sterilization

A

killing C. botulinum endospores from canned goods

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6
Q

Disinfection:

A

destroying harmful microorganisms

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7
Q

Antisepsis:

A

destroying harmful microorganisms from living tissue

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8
Q

Degerming

A

the mechanical removal of microbes from a limited area

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9
Q

Sanitization

A

lowering microbial counts on eating utensils to safe levels

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10
Q

Biocide (germicide):

A

treatments that kill microbes

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11
Q

Bacteriostasis:

A

inhibiting, not killing, microbes

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12
Q

(rate of microbial death) Effectiveness of treatment depends on:

A

1) Number of microbes
2) Environment (organic matter, temperature, biofilms)
3) Time of exposure
4) Microbial characteristics

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13
Q

Actions of Microbial Control Agents

A

1) Alteration of membrane permeability
2) Damage to proteins (enzymes)
3) Damage to nucleic acids

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14
Q

Thermal death point (TDP):

A

lowest temperature at which all cells in a liquid culture are killed in 10 min

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15
Q

Thermal death time (TDT):

A

minimal time for all bacteria in a liquid culture to be killed at a particular temperature

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16
Q

what does heat do to enzymes

A

denatures

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17
Q

Decimal reduction time (DRT)

A

Minutes to kill 90% of a population at a given temperature

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18
Q

Moist Heat Sterilization

A

1) Moist heat denatures proteins
2) Boiling
3) Free-flowing steam

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19
Q

Autoclave

A
  • steam under pressure
  • 121 C at 15 psi for 15 min
  • Kills all organisms and endospores
  • Steam must contact the item’s surface
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20
Q

Moist Heat Sterilization

A

Large containers require longer sterilization times

Test strips are used to indicate sterility

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21
Q

Pasteurization

A

reduces spoilage organisms and pathogens

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22
Q

Thermoduric

A

organisms survive

23
Q

Dry Heat Sterilization

A

Kills by oxidation

  • Flaming
  • Incineration
  • Hot-air sterilization
24
Q

Filtration is the

A

Passage of substance through a screenlike material

25
Q

filtration is used for

A

heat-sensitive materials

26
Q

Two types of filters

A

1) High-efficiency particulate air (HEPA) filters
- remove microbes > 0.3 µm

2) Membrane filters
- remove microbes > 0.22 µm

27
Q

Physical Methods of Microbial Control

A

1) Low Temp
2) High Pressure
3) Desiccation
4) osmotic pressure

28
Q

Low temp and microbial control

A

Low temperature has a bacteriostatic effect

Examples

  • Refrigeration
  • Deep-freezing
  • Lyophilization (freeze drying)
29
Q

High pressure and microbial control

A

denatures proteins

30
Q

Desiccation and microbial control

A

absence of water prevents metabolism

31
Q

Osmotic pressure and microbial control

A

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

32
Q

Radiation types

A

Ionizing radiation

Non ionizing radiation

Microwaves

33
Q

Ionizing radiation

A

(X rays, gamma rays, electron beams)

1) Ionizes water to create reactive hydroxyl radicals
2) Damages DNA by causing lethal mutations

34
Q

Nonionizing radiation

A

(UV, 260 nm)

Damages DNA by creating thymine dimers

35
Q

Microwaves

A

kill by heat; not especially antimicrobial

36
Q

Principles of Effective Disinfection

A

1) Concentration of disinfectant
2) Organic matter
3) pH
4) Time

37
Q

Dilution Tests

A

1) Metal cylinders are dipped in test bacteria and dried
2) Cylinders are placed in disinfectant for 10 min at 20°C
3) Cylinders are transferred to culture media to determine whether the bacteria survived treatment

38
Q

The Disk-Diffusion Method

A

1) Evaluates efficacy of chemical agents
2) Filter paper disks are soaked in a chemical and placed on a culture
3) Look for zone of inhibition around disks

39
Q

Phenol and Phenolics

A

Injure lipids of plasma membranes, causing leakage

40
Q

Bisphenols

A

1) Contain two phenol groups connected by a bridge
2) Hexachlorophene and triclosan
3) Disrupt plasma membranes

41
Q

Biguanides

A

1) Chlorhexidine
2) Used in surgical hand scrubs
3) Disrupt plasma membranes

42
Q

Halogens

A

Iodine

Chlorine

43
Q

Iodine

A

is a halogen

1) Tincture: solution in aqueous alcohol
2) Iodophor: combined with organic molecules
3) Impairs protein synthesis and alters membranes

44
Q

Chlorine

A

is a halogen

1) Oxidizing agents; shut down cellular enzyme systems
2) Bleach: hypochlorous acid (HOCl)
3) Chloramine: chlorine + ammonia

45
Q

Alcohols

A

1) Denature proteins and dissolves lipids
2) No effect on endospores and nonenveloped viruses

3) Ethanol and isopropanol
- Require water

46
Q

Heavy Metals and Their Compounds

A

Oligodynamic action—very small amounts exert antimicrobial activity

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
47
Q

Chemical Food Preservatives

A

1) Sulfur dioxide prevents wine spoilage

2) Organic acids
- Inhibit metabolism
- Sorbic acid, benzoic acid, and calcium propionate prevent molds in acidic foods

3) Nitrites and nitrates prevent endospore germination

48
Q

Antibiotics

A

Bacteriocins—proteins produced by one bacterium that inhibits another

Nisin and natamycin prevent spoilage of cheese

49
Q

Aldehydes inactivate

A

proteins by cross-linking with functional groups

50
Q

Aldehydes are used

A

for preserving specimens and in medical equipment

examples:
-Formaldehyde and ortho-phthalaldehyde

-Glutaraldehyde is one of the few liquid chemical sterilizing agents

51
Q

Chemical Sterilization

A

1) Gaseous sterilants cause alkylation—replacing hydrogen atoms of a chemical group with a free radical
2) Cross-links nucleic acids and proteins

3) Used for heat-sensitive material
Ethylene oxide

52
Q

Plasma

A

1) Fourth state of matter, consisting of electrically excited gas
2) Free radicals destroy microbes
3) Used for tubular instruments

53
Q

Supercritical Fluids

A

1) CO2 with gaseous and liquid properties

2) Used for medical implants

54
Q

Peroxygens and Other Forms of Oxygen

A

1) Oxidizing agents

2) Used for contaminated surfaces and food packaging
O3, H2O2, and peracetic acid

Microbiology (9 decks)

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