Antisepsis and Sterilization

Question 1

What is the germ theory?

Answer 1

The proposal that microorganisms cause disease.

Question 2

What is Koch’s first postulate?

Answer 2

The microbe must be present in all disease cases

Question 3

What is Koch’s second postulate?

Answer 3

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

Question 4

What is Koch’s Third postulate?

Answer 4

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

Question 5

What is Koch’s Fourth Postulate ?

Answer 5

The microbe must be isolated from a purposely infected host.

Question 6

What is a Nosocomial Infection?

Answer 6

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

** Therefore they are thought to be hospital acquired.

Question 7

How long after treatment is an infection considered nosocomial?

Answer 7

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

Question 8

Why are infection rates so high in healthcare facilities?

Answer 8

Because they are full of lots of sick people.

Question 9

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

Answer 9

Proper hand hygiene

Question 10

What is a disinfectant ?

Answer 10

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

Question 11

What is an antiseptic ?

Answer 11

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

Question 12

What is a bacteriostatic agent?

Answer 12

Agents that inhibit bacterial growth

Question 13

What is a bactericidal agent?

Answer 13

Agents that destroy or inactivate bacteria

Question 14

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

Answer 14

They denature proteins and disrupt cell membranes.

**They are ineffective against spores protozoan and cysts

Question 15

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

Answer 15

Chlorhexidine

Question 16

What is Isopropyl alcohol?

Answer 16

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

Question 17

How does iodine kill bacteria?

Answer 17

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

Question 18

What is an iodine detergent?

Answer 18

Iodophores

Question 19

What is chlorine used for?

Answer 19

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.

Question 20

Compare the effectiveness of halogens to phenolics or alcohols.

Answer 20

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

Question 21

How does surfactant act as an antimicrobial agent?

Answer 21

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

Question 22

What are Quaternary ammonium compounds?

Answer 22

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

Question 23

What is Glutaraldehyde and what is it used for?

Answer 23

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

Question 24

How does gludaraldehyde work ?

Answer 24

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.

Question 25

What is ethylene oxide gas?

Answer 25

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.

Question 26

What is the advantage of ethylene oxide gas?

Answer 26

It thoroughly sterilizes everything.

Question 27

How does hydrogen peroxide work?

Answer 27

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.

Question 28

What is sterilization?

Answer 28

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

Question 29

In regard to sterilization how are bacteria killed over time?

Answer 29

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

Question 30

What can alter death rate kinetics?

Answer 30

Mixed microbial populations will alter the death rate kinetics.

Question 31

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

Answer 31

Heat, Cold, Filtration, and Radiation

Question 32

What does high heat do to microbial organisms?

Answer 32

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

Question 33

How does an autoclave kill microorganisms

Answer 33

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

Question 34

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

Answer 34

Autoclaving at 15psi and 121 degrees Celsius

Question 35

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

Answer 35

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

Question 36

What is pasteurization?

Answer 36

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%.

Question 37

What does refrigeration and freezing do to microbial organisms?

Answer 37

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.

Question 38

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

Answer 38

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

Question 39

What is the disadvantage of cellulose filtering?

Answer 39

Viruses can pass through the pores.

Question 40

How does nonionizing radiation kill bacteria?

Answer 40

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

Question 41

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

Answer 41

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

Question 42

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

Answer 42

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

Question 43

What is short wave ionizing radiation used for>

Answer 43

For the sterilization of disposable operating room products and foodstuff.

Question 44

What is chlorhexidine?

Answer 44

A topical phenolic that alters the membrane permeability of bacteria.