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Microbiology-1 > Antisepsis and Sterilization > Flashcards

Antisepsis and Sterilization Flashcards

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Biology 101 flashcards
1
Q

What is the germ theory?

A

The proposal that microorganisms cause disease.

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2
Q

What is Koch’s first postulate?

A

The microbe must be present in all disease cases

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3
Q

What is Koch’s second postulate?

A

The microbe must be isolated from the infected host and grown in pure culture.

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4
Q

What is Koch’s Third postulate?

A

When a pure culture is introduced into a susceptible host the disease must be reproduced.

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5
Q

What is Koch’s Fourth Postulate ?

A

The microbe must be isolated from a purposely infected host.

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6
Q

What is a Nosocomial Infection?

A

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

** Therefore they are thought to be hospital acquired.

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7
Q

How long after treatment is an infection considered nosocomial?

A

It can occure within 6-12 months of systemic antibiotic treatment. This can be included with Long term care facility, Central IV cathetarization,

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8
Q

Why are infection rates so high in healthcare facilities?

A

Because they are full of lots of sick people.

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9
Q

What is the most important method to limit the transmission of nosocomial agents?

A

Proper hand hygiene

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10
Q

What is a disinfectant ?

A

A physical or chemical agent used to inhibit or destroy microorganisms on INANIMATE OBJECTS

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11
Q

What is an antiseptic ?

A

A physical or chemical agent used to inhibit or destroy microorganisms on skin or other tissue.

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12
Q

What is a bacteriostatic agent?

A

Agents that inhibit bacterial growth

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13
Q

What is a bactericidal agent?

A

Agents that destroy or inactivate bacteria

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14
Q

What are phenolics and alcohols effective against and how do they destroy bacteria?

A

They denature proteins and disrupt cell membranes.

**They are ineffective against spores protozoan and cysts

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15
Q

What is a topical phenolic that alters membrane permeability of bacteria?

A

Chlorhexidine

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16
Q

What is Isopropyl alcohol?

A

An antiseptic. IT must contain water to be effective ( 70% )

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17
Q

How does iodine kill bacteria?

A

Iodine is a halogen and works by iodinating or oxidizing bacterial proteins.

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18
Q

What is an iodine detergent?

A

Iodophores

19
Q

What is chlorine used for?

A

Chlorine is another halogen that oxidises protein. It is not suitable for antiseptic use but is effective in decontaminating water and hypochlorite is useful in cleaning surfaces.

20
Q

Compare the effectiveness of halogens to phenolics or alcohols.

A

Halogens are effective against bacteria spores and most viruses. AND ARE THEREFORE MORE EFFECTIVE THAN PHENOLICS OR ALCOHOLS

21
Q

How does surfactant act as an antimicrobial agent?

A

Surfactants conatin hydrophopic and hydrophilic groups that perturb bacterial membranes leading to cell death.

22
Q

What are Quaternary ammonium compounds?

A

QUATS are cationic detergentssued at 0.1% concentration as antiseptics. They are not used today because they are ineffective against spores and viruses.

23
Q

What is Glutaraldehyde and what is it used for?

A

Glutaraldehyde is an alkylating agent that is used to disinfect equipment.

24
Q

How does gludaraldehyde work ?

A

First it polymerizes and then binds to proteins in the outer membrane of gram negative bacteria.
It also binds to the peptidoglycan in the cell wall of gram positive bacteria.

25
Q

What is ethylene oxide gas?

A

Ethylene oxide gas is also an alkylating agent and is used to treat heat-liable equipment.
**Explosive and mutagenic. Also very hazardous to the skin and must be used under very tightly controlled conditions.

26
Q

What is the advantage of ethylene oxide gas?

A

It thoroughly sterilizes everything.

27
Q

How does hydrogen peroxide work?

A

Works via oxidation. It attacks the lipids in the cellular membrane and other cellular components of bacteria.

**It is not very effective against spores and catalyze positive bacteria.

28
Q

What is sterilization?

A

The complete killing or removal of living organisms from a device or area.

29
Q

In regard to sterilization how are bacteria killed over time?

A

Bacteria are exponentially killed over time. 90% every ten minutes.

30
Q

What can alter death rate kinetics?

A

Mixed microbial populations will alter the death rate kinetics.

31
Q

What are some of the common physical methods used to kill bacteria? Name 4

A

Heat, Cold, Filtration, and Radiation

32
Q

What does high heat do to microbial organisms?

A

High temperatures denature proteins, reduce the integrity of cell membranes and denature nucleic acids.

33
Q

How does an autoclave kill microorganisms

A

It subjects the microorganisms to steam and pressure. Moist heat kills micro organisms much more effectively than dry heat.

34
Q

What is the most effective form of sterilization for all bacteria, fungi, spores, viruses ext?

A

Autoclaving at 15psi and 121 degrees Celsius

35
Q

Compare the time and temps required for dry heat sterilization versus steam sterilization?

A

Dry heat is less effective and will thus take longer times and higher temps

36
Q

What is pasteurization?

A

Heating a liquid to 55-75 degrees celcius for 30 min and then rapidly cooling it. This does not sterilize it but it will reduce the microbial load by 90%.

37
Q

What does refrigeration and freezing do to microbial organisms?

A

Slows the growth of most all pathogens and is therefore a complement of pasteurization. They do not kill all microorganisms and have no effect on spores so are therefore not optimal.

38
Q

What is a cellulose membrane filter and how does it work?

A

Cellulose membrane filters have pore sizes of 0.2 microns. They can effectively remove live and dead microorganisms.

39
Q

What is the disadvantage of cellulose filtering?

A

Viruses can pass through the pores.

40
Q

How does nonionizing radiation kill bacteria?

A

UV rays excite electrosn and lead to the formation of new covalent bonds. One of these are thymine dimers.

41
Q

What is the disadvantage of non ionizing radiation and what is its main application?

A

UV rays have poor cellular penetration due to its long wavelength. It is commonly used to disinfect air and surfaces in hospitals.

42
Q

Wht is the advantage of X-ray and Gamma ray Ionizing radiation?

A

The transmitted energy damages DNA but also produces free radicals and creates hydrogen peroxide from cytoplasmic water.

43
Q

What is short wave ionizing radiation used for>

A

For the sterilization of disposable operating room products and foodstuff.

44
Q

What is chlorhexidine?

A

A topical phenolic that alters the membrane permeability of bacteria.

Microbiology-1 (6 decks)

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