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Topic H: Control of Microbial Growth > A: Environmental Control > Flashcards

A: Environmental Control Flashcards

1
Q

sterilization (sterilant)

A

-100% destruction of microorganisms (≠prions)
-However, only eradication of harmful microorganisms
» i.e. Commercial sterilization
» i.e. Laboratory sterilization

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2
Q

asepsis

A

Environment or procedure free of pathogens

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3
Q

Disinfection:
use of?
to?
aka?

A

-Use of Chemical methods (disinfectants) and Physical methods
–To eradicate microorganisms, especially pathogens on inanimate objects
–“Sanitation”

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4
Q

antisepsis

A

living surfaces
“antiseptics”

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5
Q

de-germing

A

-Physical/Mechanical removal of microorganisms while using chemical methods

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6
Q

method etymology

A

-static/-stasis: indicating inhibition but not complete destruction of a type of microbe
-cidal/-cide: indicating destruction of a type of microbe

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7
Q

death rate:

A

Calculation of death under strict conditions
* Eradication per minute
* Constant rate

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8
Q

external vs internal microbial considerations

A

*External: Cellular integrity: Cell Wall, Cell Membrane

*Internal: Cellular Metabolism: Proteins, Nucleic Acids

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9
Q

cell considerations include

A

protein structure
double stranded or single
gram neg or pos
cell membrane

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10
Q

factors affecting antimicrobial methods:

A

Site treated (Location):
-Patient vs. Environment
-Patient: Location, Exposure

Susceptibility: Composition

Environmental conditions:
– Temperature
– pH
– Pressure
– Radiation

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11
Q

physical methods include:

A

-Temperature: Heat, Cold
-Desiccation
-Filtration
-Osmotic Pressure
-Radiation

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12
Q

temperature:
what can heat disrupt?
terminology?

A

Heat Disrupts Proteins (Denaturation), Nucleic Acids (Melting) and Lipid Layers / Walls (Disruption)

Terminology:
–Thermal Death Point: Minimal Temp for complete microbial death in 10min
–Thermal Death Time: Minimal time for complete
microbial death at a set Temp
–Decimal Reduction Time

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13
Q

moist heat:

A

-Employed for Convection: Air vs. Water
-Boiling”:
– ~100°C / 10min: Vegetative cells (bacteria,
fungi, protozoa, some viruses)
–Not endospores, cysts, some viruses: 20h
-Recommended for housewares and routine
utensils

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14
Q

moist heat: autoclaving

A

-Boiling limits = Steam
-Pressure combination with Heat: 15 PSI, 121°C
-Markers for sterilization: Tape, Color, Bacillus stearothermophilus

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15
Q

moist heat: pasteurization

A

-Non-sterilizing: Thermoduric, thermophilic
exceptions
-does a body good

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16
Q

dry heat:

A

-Ovens: Used when water is not an option, Decreased efficacy
–15m vs. 16h (autoclave)

Incineration
1. Air valve closed (long, flame)
2. Air valve nearly fully closed (skinnier controlled red orange flame)
3. Air valve semi-opened (purple smaller flame)
4. Air valve maximally opened (blue smallest flame)

17
Q

cold

A

-Reduction of microbial metabolism (growth & reproduction)
Refrigeration: 0C - 7C
Freezing: lower than 0C, slow freezing advantage

18
Q

drying
-desiccation
-lyophilization

A

Desiccation: Oldest method of preservation
-Removes most water: Metabolism, Propagation
-Not anti-fungal

Lyophilization:
*Freezing + Desiccation: Sublimation
*Permits reconstitution: No ice crystals

19
Q

filtration:
seperation

A

-Separation: Physical sieving with Cells or viruses
Vacuum-assisted
Glass, porcelain, cotton, asbestos
*Common: Nitrocellulose: 0.01μm-25μm

20
Q

osmosis:
osmotic pressure

A

-Osmotic Pressure: High concentrations of
solutes like Salt or Sugar
-Hypertonic solutions: Crenation (desiccation)
-Used for preservation: Not anti-fungal

21
Q

radiation:
what is it?
types?

A

-Particulate & Electromagnetic. it is High-speed traveling at Light (3 x108 m/s). it has Subatomic particles (Particulate) like Protons. it has Energy Emission by Waves. Wavelength-based are γ-rays, x-rays, and UV.

Radiation Types:
* Ionizing: < 1nm λ, Remove electrons (Ionizing), Affect Bonds and ROS’s. Causes Denaturation and Mutation. Types include e neg. beams, γ-rays, x-rays. Commonly used in food ~ Near UV
-ultraviolet, x-rays, gamma rays
-radioactive chemicals, x-rays, sun

  • Non-ionizing: > 1nm λ. Causes Denaturation and Mutation
    – **UV (260nm)
    -infrared, microwaves, radio waves,
    -tv remote, radar, cell phones, TV, FM/AM
22
Q

compounds:
phenolics?
cons?

A

-Phenol(ics): a.k.a. Carbolic acid, standard of comparison

23
Q

alcohols

A

-Largely non-polar: Require water for efficacy, May be combined with other antimicrobial agents like Tinctures
-Effective towards Bacteria, Fungi, Viruses
-Not-Effective towards Endospores, fungal spores
-Reps:
Isopropanol [IPA], Ethanol
[EtOH]

24
Q

halogens

A

-Gp VIIA on Periodic Table: I, Cl, Br, F and ILGs
-Putative oxidizers: Anti-enzymatic
-Effective: Vegetative bacteria, some spores (bacterial, fungal), and protozoan cysts
-Reps:
– Iodine, NaOCl, CaOCl, F

25
Q

oxidizers

A

-Loss of e- ≡ Oxidation
-HLGs: Anti-enzymatic, Notable against anaerobes (Deep wounds)
-Reps:
Peroxides, Ozone, Peracetic Acid (Sporicide)

26
Q

surfactants

A

-Decrease surface tension
-Increase concentration of antimicrobial
-LLGs: Bacteria (G+), Fungi, Env. Viruses
Reps:
-Soaps: Bipolar compounds, Concentrate oil + organisms
-Detergents: Cationic compounds (Quaternary NH4+), Disrupt membranes

27
Q

what are the chemical substances methods?

A

phenolics
alcohol
halogens
oxidizers
surfactants
aldehydes
gases

28
Q

elements:

A

-Heavy Metals:
-Sulfur-chelating metals: Zn, Hg, Ag, Cu
-Anti-enzymatic: Denatures proteins
-LLGs
-Reps:
–Ag: Silver bullets
–Hg: Thimerosal
–Cu: Water-based treatments

29
Q

aldehydes

A

-Functional Group
-Cross-linker
-Anti-enzymatic: Denatures protein amino, hydroxyl, sulfhydryl, and carboxyl groups
-Anti-Nucleic Acid: Permanently cross-links DNA + RNA
-Reps:
–Formaldehyde: Formalin (37%), Preservative

30
Q

gases:

A

-Bulk-based cross-linker
-Chamber-based
-Cons: Low-efficacy, Carcinogenic
-Reps:
–Ethylene oxide, propylene oxide, and beta-propiolactone

31
Q

organics:

A

-Enzymes:
-Natural methods: Tears, Saliva, Gastrics
-Sources: Human, Fungal, Bacterial
-“Antimicrobials”
-Cutting-edge research: Animals

32
Q

LLG

A

Low Level Germicides
-enveloped viruses
-gram-postive bacteria
-naked viruses

33
Q

ILG

A

Intermediate Level Germicides
-fungi
-gram-negative bacteria
-protozoa (trophozoites)

34
Q

HLG

A

High Level Germicides
-protozoan
-cysts
-mycobacteria
-endospores
-prions (highest)

Topic H: Control of Microbial Growth (2 decks)

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