Sterilization and Disinfection...

Question 1

Sterilization

Answer 1

total destruction or physical removal of all microorgamism

Question 2

Moist heat

Answer 2

most widely used/dependable method of sterilization

Question 3

How does moist heat kill microbes

Answer 3

by irreversibly denaturing proteins, compromising membrane integrity

Question 4

Dry heat

Answer 4

kills spores but may not eliminate pyrogens

Question 5

When is dry heat used

Answer 5

only for materials that can be damaged by moist heart or where moist heat can’t get to

Question 6

How does dry heat kill microbes

Answer 6

by irreversibly denaturing proteins, compromising membrane integrity

Question 7

Ethyele oxide gas

Answer 7

colorless gas that is highly toxic, flammable and explosive

Question 8

When is ethyele oxide gas used

Answer 8

for heat and moisture sensitive medical devices without deleterious effects on the material used

Question 9

How does ethylene oxide gas kill microbes

Answer 9

by alkylating protein, DNA, and RNA within cells, which prevents normal cellular metabolism and replication

Question 10

UV Irradation

Answer 10

used in laboratory safety cabinets, hospital operating rooms, ionizing, prevention of growth in water in apparatus, inefficient as a sterilant

Question 11

Ionizing radiations

Answer 11

used to sterilize heat sensitive, pre-packed, single use plastic items

Question 12

How do ionizing radiations kill microbes

Answer 12

by eliciting DNA damage through production of free radical, blocks microbial replication

Question 13

Disinfection

Answer 13

process of removing or killing most, but not all, viable organisms. More resilient organisms like mycobacteria, viruses, fungi and bacterial spores may survive these procedures.

Question 14

Factions that influence effectiveness of disinfection

Answer 14

i. Nature of the item to be disinfected
ii. Concentration of disinfectant
iii. Duration and temp of exposure
iv. Number and resilience of the containing orgasm
v. Amount of organic material present on the device, which can inactivate the disinfectant

Question 15

HIgh level disinfection

Answer 15

can kill everything except lots of spores

Question 16

What is high level disinfection used for

Answer 16

all devices that can’t be sterilized

Question 17

examples of high level disinfection

Answer 17

glutaraldehyde, oxidizing agent

Question 18

Intermediate level disinfection

Answer 18

i. can kill mycobacteria, bacteria, most viruses, most fungi but are not very effective against bacterial spores.

Question 19

Examples of intermediate level disinfection

Answer 19

alcohols, iodine containing compounds (iodophors), phenolic compounds

Question 20

When is intermediate level disinfection used

Answer 20

semi-critical instruments which are unlikely to be contaminated with spores and only come into contact with mucus membranes or non-intact skin

Question 21

low level disinfectants

Answer 21

can kill most vegetative bacteria, some fungi, and some viruses in a reasonable period of time

Question 22

Examples of low level disinfectants

Answer 22

quaternary ammonium compounds

Question 23

Antisepsis

Answer 23

Antiseptic agents are disinfectants used to lower the number of microorganisms on skin surfaces. None of these agents kill bacterial spores however they are all very efficacious against vegetative bacteria and are very safe.

Question 24

Alcohols

Answer 24

kill most microbes but not spores
no residual killing effect
readily inactivated by organic matter
not as affective as iodine containing compounds

Question 25

How do alcohols lower number of microbes

Answer 25

denaturation of bacterial proteins, but can also inhibit the synthesis of metabolites essential for rapid cell division

Question 26

Which type of alcohol is more effective - 70% or 95%

Answer 26

70%

Question 27

How do phenolic compounds work

Answer 27

penerate and disrupt the cell wall in high conc.
denature proteins and lipids within the cytoplasmic membrane
lyse cells
rarely used
antimicrobial action improved by halogens

Question 28

Iodine containing solutions

Answer 28

most effective

need before obtaining a blood culture and when putting in caths

Question 29

Ticture of iodine

Answer 29

good for before a blood culture, but irritates skin

Question 30

iodophors

Answer 30

stable, non-toxic for skin and tissue

Question 31

How is the toxicity of iodine compared to alcohols

Answer 31

slightly more toxic

Question 32

how does iodine work

Answer 32

can quickly penetrate the cell wall of microorganisms and cause disruption of proteins and nucleic acid structure and synthesis

Question 33

Clorehexidine

Answer 33

has broad antimicrobial activity but slower rate of killing than alcohol

Question 34

How does clorehexidine work

Answer 34

membrane disruption

Question 35

When is chlorehexidine used

Answer 35

for general skin cleaning, a surgical scrub, and pre-operative skin prep

Question 36

Resideual activity of chlorehexidine

Answer 36

some residual activity, but diminished by organic matter and high pH

Question 37

Quaternary ammonium compounds

Answer 37

attack energy producing enzymes, denature cell proteins and disrupt the cell membranes
not very effective

Question 38

Triclosan

Answer 38

found in antiseptic hand soap, toothpaste

active against bacteria, but not spores

Question 39

How does triclosan work

Answer 39

inihibts bacterial lipid synthesis and may also disrupt the cell membrane at high concentration