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BIO 220 [Exam #4] > Chapter 7 - The Control of Microbial Growth > Flashcards

Chapter 7 - The Control of Microbial Growth Flashcards

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1
Q

Define: Aseptic techniques
Include examples

A

practices and procedures to prevent contamination from microbes (ex: use fire source, spray disinfectant)

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1
Q

Compare: Sepsis vs. Asepsis

A

Sepsis
- microbe contamination

Asepsis
- absense of significant contamination

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2
Q

Compare: Sterilization vs. Disinfection

A

Sterilization

  • removing and destroying ALL microbial life (kills all active cells + endospores)

Disinfection

  • destroys MOST microbes (doesnt kill endospores)
  • usually applies to non-living objects (counter/surfaces)
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3
Q

Define: Antisepsis

A

destorying harmful microbes from living tissue/body wounds

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4
Q

Define: Degerming

Include: How its accomplished, examples

A

physical removal of microbes from a limited area

  • accomplished by soaps/detergents
  • Ex: hand washing, wiping skin with alcohol swab
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5
Q

Define: Sanitization
Include: examples

A

cleansing of fomites to remove enough microbes to achieve levels safe for public health

Ex: Restaurant industry lowers microbial count (doesnt kill eveything) on plates and eating utensils to safe levels

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6
Q

Compare: Biocide (germicide) vs Biostatic (bacteriostatic)

Include: Examples of biocide

A

Biocide (germicide)

  • chemical treatement that kill microbes; can be target specific
  • Ex: bactericide, fungicide, viricide

Biostatic (bacteriostatic)

  • treatment that inhibits growth of microbes
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7
Q

List several factors (4) that affect the rate of microbial death

A

1. # of microbes (population load)

  • higher the population load = longer time to kill

2. environment (pH, nutrients, temp)

  • ideal environment will take longer to kill

3. time of exposure to disinfectant

4. microbial characteristics

  • range from most resistant microbes (difficult to kill) to most sesnsitive microbes (easy to kill)
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8
Q

Know the 2 most resistant “microbes” (to chemical agents) and the 2 most senstive “microbes” (to chemical agents)

A

MOST RESISTANT

  • prions
  • bacteria containing endospores

LEAST RESISTANT

  • Gram positive bacteria
  • Viruses with lipid envelops
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9
Q

Name four ways chemical agents are able to control microbial growth

(Hint: How do these chemical agents harm the microbe?)

A

1. Alter cell membrane permeability

  • damage CM of bacteria = distrupt homeostasis

2. Damage to proteins (enzymes)
3. Damage to nucleic acids (DNA)

  • damage DNA -> damage RNA -> damage protein structure -> loss of protein structure/FXN

4. Inhibit/alter metabolism

  • damage cell resp -> little/no energy (ATP)
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10
Q

Understand the concepts of Thermal Death Point (TDP) and Thermal Death Time (TDT)

A

Thermal Death Point (TDP)

  • lowest temperature (variable) at which all cells in a liquid culture are killed in 10 minutes (fixed)

Thermal Death Time (TDT)

  • minimal time (variable) for all bacteria in a liquid culture to be killed at a certain temperature (fixed)
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11
Q

Examples: Boiling H2O at 100C for 10 minutes

What is the TDP and what is the TDT?

A

TDP = 100C
TDT = 10 minutes

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12
Q

Describe this Physical Method: Dry Heat

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Kills via oxidation (disrupt CW)
    -> also seen with halogens

Examples:

  • Bake Sterilization (BS)
  • Hot-Air Sterilization (HAS)
  • Direct Flaming (DF)
  • Incineration (I)

Application/Uses:

  • Glassware (BS, HAS)
  • Metal instruments (DF)
  • Prions (I)
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13
Q

Describe this Physical Method: Moist Heat

Include: Mechanism of Action, Examples, Applications, MISC (Types of Pastuerization and Advantages of Pastuerization)

A

Mechanism of Action:

  • Kills via protein (enzyme) denaturation

Examples:

  • Boiling (B)
  • Autoclave (A)
    -> Inv steam under pressure (psi)
    -> Kills ALL organisms and endospores
  • Pasteruization
    -> Inv use of various combination of temp and heating times

Application/Uses:

  • Glassware (B, A)
  • Metal Instrucments (A)
  • Lab Media/Plates/Tubes (A)
  • Food/Beverages; Dairy/Juices (P)

MISC:

Types of Pastuerization:

  • Bulk-liquid pasteurization
  • High-temperature short time (HTST)
  • Ultra-High-Temperature (UHT)

Advantages of Pasteurization:

  • Kills pathogens (but not spores)
  • Extends shelf life
  • Keep quality taste
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14
Q

Describe this Physical Method: Low Temperatures

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Low temperature has a bacteriostatic effect (suppress growth)

Examples:

  • Refridgeration (R)
    -> Extends shelf life
  • Deep-Freezing (DF)
  • Lyophilization (L)
    -> Freeze drying method (powder) used for long-term/indefinitie preservation

Application/Uses:

  • Medications/Antibiotics (R)
  • Hormones (R)
  • Meats (DF)
  • Some foods/Microbial culture (L)
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15
Q

Describe this Physical Method: Filtration

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Passage of substances/fluids through screen-like membrane

Examples:

  • High-Efficiency Particulate Air (HEPA) Filter
    -> Removes tiny microbes
  • Membrane Filters
    -> Removes VERY TINY microbes (viruses, large proteins)

Application/Uses:
Used for heat sensitive materials:

  • Vaccines
  • Serum
  • Enzymes
16
Q

Describe this Physical Method: Dessication

Include: Mechanism of Action, Applications

A

Mechanism of Action:

  • Removal of water
    -> no water = Pvt metabolism = no cell resp = no ATP (energy)

Examples:

  • x

Application/Uses:

  • Salami/Pepperoni
17
Q

Describe this Physical Method: Osmotic Pressure/Imbalance

Include: Mechanism of Action, Applications

A

Mechanism of Action:

  • Removal of water
    -> Uses high concentration of salts/surgars (solutes) to create hypertonic envuronemtn = draws water away = cell (path) shrink/die

Examples:

  • x

Application/Uses:

  • Salami/Pepperoni
18
Q

Describe this Physical Method: Radiation

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Destroy/damage DNA (of microbe)

Examples:

  • Ionizing Radiation (destory DNA)
    -> Types: X-rays, Gamma Rays, Electron Beams (high E)
  • Nonioninzing Radiation (damage DNA)
    -> Types: UV light (medium/high E)

Application/Uses:

  • Disposable syringes/gloves/masks/surgical sutures (IR)
  • Cleaning hospital rooms via germicidal UV lamp (NR)
19
Q

Which example of moist heat involves pressure?

A

Autoclave (inv steam under pressure to kill ALL organisms and endospores)

20
Q

List (3) desirable attributes of a chemical agent

A
  • Safe (must be non-toxic to humans, animals, plants)
  • Effective at Low Concentrations (high concentrations can cause bodily harm)
  • Wide Range Uses (kills everything)
21
Q

List (4) factors affecting the level of disinfection (by chemical agent)

A
  • Concentration of chemical agents (conc vs. dilute)
  • Time of exposure to chemical agent
  • pH of chemical agent (want chem agent ot be acidic)
  • Type of microbes/microbial characteristics (most resistant to most sensitive microbes)
22
Q

What method is uses to evaluate the efficacy of chemical agents (to microbes)?

Describe how this method is carried out

What is one advantage and disadvantage to this method?

A

Disk Diffusion Method

  • paper disk soaked in chemical agent and placed on culture
  • look for zone of inhibition
  • Advantages: evaluate several agents at once
  • Disadvantage: chemical agents diffuse into agar at different rates
23
Q

Describe this Chemical Method: Phenols, Phenolics, Bisphenols, Biguanides

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Disruption of plasma membrane
    -> Cell leakage = disrupt homeostasis

Examples:

  • Phenol (1)
    -> Rarely used, highly irritating to skin & strong odor
  • Phenolics (2)
    -> Derived from Phenol
  • Bisphenols (3)
  • Biguanides (4)

Application/Uses:

  • Hand soaps (3)
  • Skin disinfection/Surgical hand scrubbing (4)
24
Q

Describe this Chemical Method: Halogens

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Kills via oxidation
    -> Also seen with dry heat

Examples:

  • Iodine
    -> Tincture (iodine + alcohol): antiseptic solution for disinfection
  • Chlorine
    -> Bleach: exist gas/liquid form; used for disinfection

Application/Uses:

  • Minor wounds (T)
  • Before/After surgery (T)
  • Water (B)
  • Household supplies (B)
  • Glassware (B)
25
Q

Describe this Chemical Method: Alcohol

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Denature proteins
  • Dissolve lipids

Examples:

  • Isopropanol
    -> Bactericidal/Fungicidal
    -> More effective in water (ex: 70%)

Application/Uses:

  • Surfaces
  • Hands
26
Q

Describe this Chemical Method: Surface-Active Agents

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Disrupt cell membranes

Examples:

  • Soap/Detergent (S/D)
  • Acid-anionic sanitizers (AAS)
  • QUATS

Application/Uses:

  • Skin degerming agent (S/D)
  • Sanitization of large metal containers in food-processing industries (AAS)
  • Used on hospital instruments, utenzils, rubber goods (QUATS)
27
Q

Describe this Chemical Method: Chemical Food Perservatives

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Inhibit metabolism (OA)
  • Pvt endospore germination in foods (N)

Examples:

  • Organic acids (OA)
    -> Pvt mold/bactria in food/cosmetics
  • Nitries/Nitrates (N)
    -> Pvt growth C. botulinum in food

Application/Uses:

  • Food/cosmetics (OA)
  • Cold cuts, hot dogs (N)
28
Q

Describe this Chemical Method: Chemical Sterilization

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Causes alkylation (uses gas to serilize)
    -> Formation of free radicals (toxic)

Examples:

  • Ethylene Oxide (gas)

Application/Uses:

  • Large, heat sensitive material/Mattresses
29
Q

Describe this Chemical Method: Plasma Sterilization

Include: Mechanism of Action, Examples, Applications

A

Mechanism of Action:

  • Causes alkylation
    -> formation of free radicals (toxic)

Examples:

  • Plasma
    -> Better penetration power and more expensive that Ethylene Oxide (regular gas)

Application/Uses:

  • Tubular Medical Instruments
    -> Surgical steel rods/plates
30
Q

Define/Describe: Plasma

A

fourth stage of matter consisting of electrically excited (charged/ionic) gas

BIO 220 [Exam #4] (8 decks)

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