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Microbiology 455 > Ch 12- Control of Microbial Growth > Flashcards

Ch 12- Control of Microbial Growth Flashcards

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Biology 101 flashcards
1
Q

Ionizing Radiation

A

Ionizes water to create hydroxyl radicals (ROS) that damage DNA
Ex. X-rays, gamma rays, electron beams

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2
Q

Nonionizing Radiation

A

Damages DNA by creating thymine dimers that inhibit DNA replication
Ex. UV, 260nm

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3
Q

Microwaves

A

Kill by heat

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4
Q

High-Efficiency Particulate Air Filters (HEPA Filters)

A

Remove microbes >0.3 um from air in clean rooms

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5
Q

Membrane Liquid Filters

A

Remove microbes >0.22 um from liquids. Used for heat-sensitive materials. Filters all microbes except viruses.

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6
Q

Use-dilution Test

A

Metal cylinders are dipped into test bacteria & dried
Cylinders are place in disinfectant for 10min at room temp
Cylinders are transferred to culture media to determine bacterial survival rate

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7
Q

Disk-diffusion Test

A

For chemical and antibiotics.
Evaluates efficacy of chemical agents
Filter paper disks are soaked in a chemical and place on inoculated bacteria plate
Look for zone of inhibition around disks

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8
Q

In-use Test

A

For disinfectant solution already in use

Evaluates microbial contamination of cleaning solutions

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9
Q

Alcohols (Chemical Disinfectant)

A

Denature proteins & dissolve phospholipids in bacteria, fungi, and enveloped viruses
Does nothing to endospores or non-enveloped viruses

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10
Q

Peroxygens

A

Oxidizing Agents

Ex. Hydrogen peroxide, Peracetic acid, Benzoyl, Ozone

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11
Q

Hydrogen Peroxide (H2O2)

A

Kills: bacteria, viruses, fungi, endospores on inanimate objects
(not for wounds; human catalase)

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12
Q

Peracetic Acid (peroxyactic acid/PAA)

A

Kills: endospores, viruses, fungi, bacteria

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13
Q

Plasma

A

Electrically Excited Gas, 4th state of matter.

Kills: bacteria, viruses, fungi, endospores

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14
Q

Heavy Metals (Chemical Disinfectant)

A

Denature proteins
Just as toxic to humans
Uses/Ex. silver nitrate is used to prevent ophthalmia neonatorum, Mercuric chloride prevents mildew in paint, copper sulfate in algicide, zinc chloride in mouthwash

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15
Q

Halogens (Chemical Disinfectant)

A

Iodine
Chlorine gas & hypochlorites
Bleach
Chloramine

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16
Q

Iodine

A 
One of the oldest disinfectants 
Oxidizing agent (damage sulfur containing amino acids, nucleotides, fatty acids)
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17
Q

Tincture

A

Solution in aqueous alcohol

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18
Q

Iodophor

A

Combined with organic molecules (povidone-iodine like Betadine)

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19
Q

Chlorine Gas & hypochlorite

A

Reacts with water to form hypochlorous acid

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20
Q

Hypochlorous Acid

A

Strong oxidizing agent that damages sulfur-containing amino acids, nucleotides, and fatty acids

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21
Q

Bleach

A

Sodium hypochlorite

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22
Q

Chloramine

A

Chlorine + ammonia

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23
Q

Phenolics & bisphenols

A

Damage phospholipids of plasma membranes causing leakage

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24
Q

Bisbiguanides

A

Damage phospholipids of plasma membranes. Effective against Gram-pos. bacteria, yeast, enveloped viruses, some Gram-neg. bacteria
Ex. Chlorhexidine

25
Q

Aldehydes (alkylating agents)

A

Very effective disinfectants. Inactivate proteins by cross-linking with some amino acid functional groups.
Kills: bacteria, viruses, fungi, endospores
Uses: specimen preservation
Ex. Formaldehyde (formalin), Glutaraldehyde (used in hospitals)

26
Q

Chemical Sterilization

A

Uses sterilant to cause alkylation

Ex. Ethylene oxide

27
Q

Alkylation

A

Replacing hydrogen atoms of a chemical group with a free radical

28
Q

Requirements for Growth

A
  • Oxygen
  • pH
  • Temperature
  • Osmotic Pressure
  • Carbon
29
Q

Sepsis

A

Microbial contamination

30
Q

Asepsis

A

The absence of significant contamination

31
Q

Aseptic Techniques

A

Prevent the microbial contamination

32
Q

Biocide (germicide)

A

Treatments that kill microbes

33
Q

Bacteriostasis

A

Inhibiting microbes

34
Q

Bacteriocide

A

Killing microbes

35
Q

Biosafety Levels

A

1-4, provide standardized ways to communicate laboratory hazard levels, range from non-harmful to deadly and contagious.

36
Q

BSL 1

A

Minimal Risk. Microbes are not known to cause disease in healthy people. (Ex. E. coli)

37
Q

BSL 2

A

Moderate Risk. Microbes are generally indigenous and are associated with various diseases that can be treated if needed. (Ex. S. aureus)

38
Q

BSL 3

A

Indigenous and/or exotic microbes that cause serious or potentially fatal diseases via respiratory transmission. (Ex. M. tuberculosis)

39
Q

BSL 4

A

Highest level. Microbes are dangerous and exotic. High risk of aerosol transmission. Frequently fatal without proper treatment/vaccines (Ex. Ebola)

40
Q

Sterilization

A

Destroying all microbial life

41
Q

Disinfection

A

Destroying harmful microbes on inanimate objects

42
Q

Antisepsis

A

Destroying harmful microorganisms on living tissue

43
Q

Degermining

A

The mechanical removal of microbes from a limited area

44
Q

Sanitation & Commercial Sterilization (Food Microbiology)

A

Sanitation - lowering microbial counts to a safe level

Commercial Sterilization - killing endospores

45
Q

Rate of Microbial Death

A

Microbes die at a constant rate.
Effectiveness of treatment depends on: Type of microbe, number of microbes, environment, composition of item, time of exposure

46
Q

Highly Resistant Microbes

A
  • Endospore Formers (Ex. Bacillus)
  • Mycobacterium Cell Wall (requires strong disinfectant)
  • Pseudomonas (will grow in disinfectants; nosocomial)
  • Non enveloped viruses (Ex. Polio)
  • Protozoan Cysts & Oocysts (Ex. Giardia)
47
Q

Microbial Control Agents

A

Kill microbes or inhibit microbial growth by: Alteration of membrane permeability, Damage/denature proteins, Damage nucleic acids.
Methods: Physical & Chemical

48
Q

Major Methods of Microbial Control

A
  • Heat or chemical sterilization
  • Physical methods of Disinfection
  • Chemical Methods of Disinfection
49
Q

Physical Methods of Disinfection

A
  • High Temperature
  • Low Temperature
  • Filtration
  • High Pressure
  • Desiccation
  • Osmotic Pressure
  • Radiation
50
Q

Thermal Death Point (TDP)

A

Lowest temperature for all bacteria in a liquid culture to be killed in 10mins
(Variable-temp; Set-time)

51
Q

Thermal Death Time (TDT)

A

Lowest time for all bacteria in a liquid culture to be killed at a particular temperature.
(Variable-time; Set-Temp)

52
Q

Decimal Reduction Time (DRT/D-value)

A

The minutes to kill 90% of a population at a given temperature
(TDP & TDT are used to determine the D-value)

53
Q

Pasteurization

A

Reduces spoilage microbes and pathogens for storages in a refrigerator.
Mild heating for a short time

54
Q

High Temperature Short Time (HTST)

A

Common form of time to temperature ration used in pasteurization

55
Q

Ultra High Temperature (UHT)

A

Used for sterilization that allows for room temperature storage.

56
Q

Low Temperature (Physical Disinfection Method)

A

Has a bacteriostatic effect

Ex. refrigeration, deep-freezing, lyophilization

57
Q

High Pressure (Pascalization)

A

Destroys microbe cells and denatures proteins without heat.

58
Q

Desiccation

A

An absence of water (prevents metabolism)

59
Q

Osmotic Pressure

A

Uses sugars or salts to create a hypertonic environment

Microbiology 455 (7 decks)

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