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MICROBIOLOGY: CMOD-Week 1 > (02) Antisepsis and Sterilization > Flashcards

(02) Antisepsis and Sterilization Flashcards

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Biology 101 flashcards
1
Q

Koch’s Postulates

A
  1. Microbe must be present in all disease cases
  2. Microbe must be isolated from the infected host and grown in a pure culture
  3. When pure culture is introduced to susceptible host the disease must be reproduced
  4. Microbe must be isolated from purposefully infected host
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2
Q

Nosocomial Infections

- assumption?

A

Infections whose onset and confirmation occur greater than 48 hours after hospitalization.

  • Assumption is that these were acquired while in the hospital
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3
Q

What infections fall under the category of Healthcare-associated infections

A
  1. Nosocomial
  2. Infections occurring within 6-12 months of systemic antibiotic treatment
  3. Residence in Long-Term Care facility
  4. Central IV catheterization
  5. Urinary Cathertization
  6. Dialysis
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4
Q

How many hospital associated infections are due to:

  • nosocomial infection
  • antibiotic resistance
A

Nosocomial = 5-10%

Antibiotic Resistance = 70%

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5
Q

3 Reasons for high rates of Hospital Associated Infections.

A
  1. Prevalence of Pathogen

2 .Prevalence of compromised patients

  1. Patient to Patient transmission by hospital personnel
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6
Q

Differentiate disinfectants and antiseptics

- which is more harsh?

A
  • Disinfectants are used an inanimate things
  • antiseptics are used on skin
  • Disinfectants are typically too harsh to use on skin
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7
Q

Differentiate bacteriostatic and bacteriocidal agents

A

Bacteriostatic
- Inhibits growth

Bacteriocidal
- Destroys or inactivates bacteria

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8
Q

What is the only chemical agent capable of eliminating all contamination?

A

Ethylene Oxide Gas

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9
Q

How do phenolics and alcohols aid in eliminating contamination?

  • effective against?
  • Ineffective against?
A

Action:

  • Denature Proteins
  • Disrupt Cell membranes

Effective against:

  • Bacteria
  • Enveloped viruses?

Ineffective against:

  • Spores
  • Protozoan cysts
  • non-enveloped viruses
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10
Q

How do halogens work to aid in eliminating contamination?

- Effective against?

A
  • Oxidize (iodinate or chloronate) proteins

Effective against:

  • Bacteria
  • Spores
  • Most Viruses
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11
Q

How do surfactants work to aid in eliminating contamination?
- what are quats?

A
  • Use hydrophobic and hydrophilic groups to disrupt cell membrane
  • quats = Quaternary Ammonium Salts, these are largely ineffective
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12
Q

Hydrogen Peroxide

  • how does it clean?
  • NOT effective against?
A
  • Attacks the Lipid Membrane

NOT Effective against:

  1. Spores
  2. Catalase (+) bacteria
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13
Q

Glyceraldehyde

  • how does it work?
  • what is it used for?
A
  • Alkylating Agent

- Used to Disinfect equipment

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14
Q

Sterilization

  • define
  • best accomplished by…
A

Definition:
- Complete Killing or Removal of All living organisms from an item or area

Best accomplished by PHYSICAL METHODS

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15
Q

How would the plot of bacterial death vs. time look?

A
  • It would be an exponential graph

**e.g. 90% (9/10) reduction of bacteria in 10 min means 99.9% (999/1000) reduction of bacteria in 30 min.

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16
Q

T or F: mixed microbial populations will alter death rate kinetics

A

True

17
Q

What are the physical methods of bacterial control?

A
  1. Temperature
  2. Filtration
  3. Radiation
18
Q

Which is more effective at killing bacteria autoclaving or baking?
why?

A

Autoclaving:
- Uses steam and pressure
(15 min at 121ºC and 15PSI)

Baking:
- Uses dry heat (pressure not needed to raise BT or h2o)
(160º for 2 hours)

AUTOCLAVING MORE EFFICIENT - wet heat is a more rapid killer than dry heat

19
Q

Why is wet heat a more rapid killer than dry heat?

A

Wet heat has H2O which can denature protein by disrupting hydrogen bonds between amino acids

20
Q

T or F: like baking and autoclaving, boiling an object STERILIZES it

A

FALSE, it does not kill spores or cysts (pretty much everything else is killed within 10 min)

21
Q

Describe the Process of Pasteurization

- does it sterilize?

A
  • Heat liquids to 55-75ºC for 30 minutes, then rapidly cool them

DOES NOT STERILIZE
- spores are not killed, bacterial load reduced by 90%

*Make liquids safe for consumption

22
Q

What does refrigeration and freezing do to prevent bacterial growth?
- does they sterilize?

A
  • Slow bacterial growth
  • Freezing may kill some bacteria by ice crystals on cytoplasm puncturing cell membrane but DOES NOT STERILIZE (no effect on spores
23
Q

Filtration

  • what does it remove?
  • What can it not remove?
A
  • Removes live and deal BACTERIA from liquids

- VIRUSES remain in the liquid (these can be removed by boiling)

24
Q

Nonionizing Radiation

  • How does it work?
  • What can it DISINFECT?
A
  • Excites electrons to form thymidine dimers in DNA

- Disinfect air and Surfaces (poor penetration so it doesn’t work on other things)

25
Q

Ionizing Radiation

  • Can it sterilize?
  • how does it work?
A
  • YES, it can sterilize disposable surgical supplies and foodstuffs

Action:

  • Damages DNA
  • Produces Free Radicals and H2O2

MICROBIOLOGY: CMOD-Week 1 (10 decks)

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