Sterilization, Disinfection and Antisepsis

Question 1

what is cross infection

Answer 1

transmission of infectious agents among patients and staff in a clinical environment

Question 2

what are cross infection risks in dentistry

Answer 2

• patients with infectious disease
• patients in the prodromal or convalescent stage of infection
• healthy carriers
• environmental sources

Question 3

what are universal precautions

Answer 3

all patients are treated as though they are a potential source of infectious pathogens

Question 4

what are the airborne routes for spread of cross infection

Answer 4

• dust borne routes: staphylococcus from skin scales, clostridium tetani from enivronmental dust
• aerosol routes: large droplets, droplet nuclei, speaking, sneezing

Question 5

what are the contact routes of cross infection

Answer 5

-person to person: direct spread by hands or clothes or fomites
- equipment: dental instruments, chairs, impression materials
- fluids: dental water supplies

Question 6

what are the sources, ,inoculation, and prevention of parenteral spread of cross infection

Answer 6

• blood, saliva, secretions
• eye, skin breach, mucous membranes, sharps injury
• training in use and disposal of sharps, Hep B vaccine, wear gloves, dress wounds

Question 7

what is sterilization

Answer 7

destruction of all microbial forms

Question 8

what is disinfection

Answer 8

destruction of most microbial forms

Question 9

what are disinfectants used on

Answer 9

inanimate objects

Question 10

what is antisepsis

Answer 10

inhibition or eliminatino of microbes on living tissue

Question 11

what are antispetics

Answer 11

chemical agents that kill or inhibit growth of microorganisms when applied to tissue

Question 12

what is sanitization

Answer 12

reduction of microbial population to levels deemed safe

Question 13

what do -cidal agents do

Answer 13

kill

Question 14

what do - static agents do

Answer 14

inhibit growth

Question 15

what is the pattern of microbial death

Answer 15

• not killed instantly
• population death occurs exponentially
• microorganisms are considered to be dead when they are unable to reproduce in conditions that normally support theirreproduction

Question 16

what are the conditions influencing the effectiveness of antimicrobial agent activity

Answer 16

-population size
- population composition
- concentration or intenstiy of an antimicrobial agent
- duration of exposure
- temperature
- local environment

Question 17

what are the use of physical methods in control

Answer 17

-heat
- low temperatures
- filtration
- radiation

Question 18

what does moist heat do

Answer 18

• effective against all types of microorganisms
• degrades nucleic acids, denatures proteins and disrupts membranes

Question 19

what is dry heat sterilization

Answer 19

• less effective, requiring higher temperatures and longer exposure times
  -oxidized cell constituents and denatures proteins

Question 20

what is thermal death time

Answer 20

shortest time needed to kill all microorganims in a suspension at a specific temperature and under defined conditions

Question 21

what is decimal reduction time

Answer 21

time required to kill 90% of microorganisms or spores in a sample at a specific temperature

Question 22

what is the Z value

Answer 22

increase in temperature required to reduce D to 10% of original value

Question 23

what do autoclaves do

Answer 23

• used to kill endospores efficiently
• used saturated steam under pressure to reach temperature above boiling

Question 24

what is pasteurization

Answer 24

controlled heating temperature well below boiling
- reduced total microbial population and thereby increases shelf life of treated material

Question 25

what is flash pasteurization

Answer 25

-high temperature short term - 72 degrees C for 15 seconds

Question 26

what is ultrahigh temperature sterilization

Answer 26

140- 150 degrees C for 1 to 3 seconds

Question 27

what does freezing do

Answer 27

-stops microbial reproduction due to lack of liquid water - some microorganisms killed by ice crystal disruption of cell membranes

Question 28

what does refrigeration do

Answer 28

slows microbial growth and reproduction

Question 29

what does filtration do

Answer 29

reduced microbial population or sterilized solutions of heat sensitive materials by removing microorganisms

Question 30

what are depth filters

Answer 30

thick fibrous or granular filters that remove microorganisms by physical screening, entrapment and or adsorption

Question 31

what are membrane filters

Answer 31

porous membranes with defined pore sizes that remove microroganisms primarily by physical screening

Question 32

what are ways to filter air in the office

Answer 32

-surgical maska - high efficiency particular air filters

Question 33

what does UV radiation do

Answer 33

limited to surface sterilization because UV radiation does not penetrate glass, dirt films, water and other substances

Question 34

what does ionizing radiation do

Answer 34

- penetrates deep into objects - destroys bacterial endospores; not always effective against viruses - used for sterilization and pasteurization of antibiotics, hormones, sutures, plastic disposable supplies and food

Question 35

what do phenolics do

Answer 35

- used as laboratory and hospital disinfectants - denature proteins and disrupt cell membranes - tuberculocidal, effective in presence of organic material and long lasting - disagreeable odor and can cause skin irritation

Question 36

what do alcohols do

Answer 36

- bactericidal, fungicidal but not sporicidal - inactivate some viruses - denature proteins and possibly dissolve membrane lipids - 60-90% in water

Question 37

what does iodine do

Answer 37

- skin antiseptic - oxidizes cell constituents and iodinates proteins - at high concentrations may kill spores - skin damage, staining, and allergies can be a problem

Question 38

what does chlorine do

Answer 38

- oxidizes cell constituents - important in disinfection of water supplies and swimming pools, used in dairy and food industries, effective household disinfectant - destroys vegetative bacteria and fungi but not spores - can react with organic matter to form carcinogenic compounds

Question 39

what do heavy metals do

Answer 39

-effective but usually toxic - combine with and inactivate proteins; may also precipitate proteins

Question 40

what do quaternary ammonium compounds do

Answer 40

- detergents: organic molecules with hydrophilic and hydrophobic ends. act as wetting agents and emulsifiers - cationic detergents are effective disinfectants: kill most bacteria but not M tuberculosis or endospores

Question 41

what do aldehydes do

Answer 41

- highly reactive molecules - sporicidal and can be used as chemical sterilants - combine with and inactivate nucleic acids and proteins

Question 42

what do sterilizing gases do

Answer 42

- used to sterilize heat sensitive materials - microbicidal and sporicidal - combine with and inactivate proteins