Sterilization and Disinfectant

Question 1

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

Answer 1

Cross-infection

Question 2

Management strategies for risk control

Answer 2

Cross-infection control:

Question 3

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

Answer 3

Universal precautions

Question 4

What are some routes of spread for cross-infection?

Answer 4

Airborne Routes
Contact Routes
Parenteral Spread of Cross-Infection

Question 5

• Staphylococcus aureus from skin scales
• Clostridium tetani from environmental dust
• these and other organisms released from solid surfaces
• sources: skin scales, wound dressings, solid surfaces

Answer 5

dust-bourne routes

Question 6

large droplets (classified as contact)

droplet nuclei

sources: speaking, sneezing, all intraoral procedures.
Massive increase when using ultrasonic scaling, air-rotor,
air/water syringe.

Answer 6

aerosol routes

Question 7

steps in the prevention of _____ _____

1. Elimination or limitation of organisms at source
2. Interruption of transmission

Answer 7

aerosol transmission

Question 8

direct spread from person-to-person by hands and clothes or
fomites (towels, etc.); large droplets (classified as contact)

prevention: hand washing, gloves, and protective clothing

Answer 8

person-to-person: contact route

Question 9

dental instruments
chairs
impression materials

prevention :
-sterilization of instruments

• use of disposals
• disinfection of dental materials
• environmental hygiene
• defining zones in the dental operatory
• disposal of infected waste

Answer 9

Equipment

Question 10

dental water supplies

prevention: flushing water supply lines, using sterile
water, and using biocide in water

Answer 10

fluids: contact routes

Question 11

Sources: blood, saliva, and secretions

Inoculation: via eye, skin breach, mucous membrane, sharps injury

prevention: training in use and disposal of sharps, hepatitis B vaccination, wearing gloves, dressing wounds

Answer 11

Parenteral Spread of Cross-infection

Question 12

– destruction of all microbial forms (including bacterial spores)

Answer 12

sterilization

Question 13

– destruction of most microbial forms
– disinfectants
• agents, usually chemical, used for disinfection • usually used on inanimate objects • high-level, intermediate-level, low-level

Answer 13

disinfection

Question 14

– Inhibition or elimination of microbes on living tissue
– antiseptics
• chemical agents that kill or inhibit growth of microorganisms when
applied to tissue

Answer 14

antisepsis

Question 15

– reduction of microbial population to levels deemed safe (based
on public health standards)

Answer 15

sanitization

Question 16

• agents that kill microorganisms or inhibit

their growth

Answer 16

Anti microbial agents

Question 17

• -cidal

Answer 17

agents kill

Question 18

• -static

Answer 18

agents inhibit growth

Question 19

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

Answer 19

T he Pattern of Microbial Death

Question 20

• population size
• population composition
• concentration or intensity of an antimicrobial
agent
• duration of exposure
• temperature
• local environment (e.g. pH, viscosity, etc.)

Answer 20

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity

Question 21

• heat • low temperatures • filtration • radiation

Answer 21

Physical Methods used in Control

Question 22

– effective against all types of microorganisms

– degrades nucleic acids, denatures proteins, and
disrupts membranes

Answer 22

moist heat

Question 23

– less effective, requiring higher temperatures and

longer exposure times – oxidizes cell constituents and denatures proteins

Answer 23

dry heat sterilization

Question 24

– shortest time needed to kill all microorganisms in a

suspension at a specific temperature and under defined conditions

Answer 24

thermal death time (TDT)

Question 25

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

Answer 25

decimal reduction time (D or D value)

Question 26

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

Answer 26

z value

Question 27

– used to kill endospores efficiently – use saturated steam under pressure to reach temperatures above boiling

Answer 27

autoclaves

Question 28

– controlled heating at temperatures well below boiling – reduces total microbial population and thereby increases shelf life of treated material

Answer 28

pasteurization

Question 29

•flash pasteurization (high temperature short-term – HTST) –72oC for 15 seconds then rapid cooling •ultrahigh-temperature (UHT) sterilization –140 to 150oC for 1 to 3 seconds

Answer 29

Pasteurization of milk

Question 30

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

Answer 30

freezing

Question 31

– slows microbial growth and reproduction

Answer 31

refrigeration

Question 32

• reduces microbial population or sterilizes solutions of heat-sensitive materials by removing microorganisms • also used to reduce microbial populations in air

Answer 32

filtration

Question 33

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

Answer 33

depth filters

Question 34

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

Answer 34

membrane filters

Question 35

• high-efficiency particulate air (HEPA) filters • surgical masks both function to

Answer 35

filter air

Question 36

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

Answer 36

ultraviolet (UV) radiation

Question 37

– 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

Answer 37

ionizing radiation

Question 38

• commonly used as laboratory and hospital disinfectants (Lysol is a mixture of phenolics) • act by denaturing proteins and disrupting cell membranes • tuberculocidal, effective in presence of organic material, and long lasting • disagreeable odor and can cause skin irritation

Answer 38

Phenolics

Question 39

* bactericidal, fungicidal, but not sporicidal * inactivate some viruses * denature proteins and possibly dissolve membrane lipids • 60%-90% in water (cidal activity drops sharply when diluted below 50% concentration)

Answer 39

Alcohols

Question 40

contain fluorine, chlorine, bromine, iodine

Answer 40

halogens

Question 41

- skin antiseptic - oxidizes cell constituents and iodinates proteins - at high concentrations may kill spores - skin damage, staining and allergies can be a problem - iodophore (iodine complexed with organic carrier)

Answer 41

iodine

Question 42

- 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 carchinogenic compunds

Answer 42

chlorine

Question 43

• e.g., ions of mercury, silver, arsenic, zinc, and copper • effective but usually toxic • combine with and inactivate proteins; may also precipitate proteins

Answer 43

heavy metals

Question 44

cetylpyridinium chloride benzalkonium chloride

Answer 44

Qua ternary Ammonium Compounds

Question 45

• detergents – organic molecules with hydrophilic and hydrophobic ends – act as wetting agents and emulsifiers • cationic detergents are effective disinfectants – kill most bacteria, but not Mycobacterium tuberculosis or endospores – safe and easy to use, but inactivated by hard water and soap

Answer 45

Qua ternary Ammonium Compounds

Question 46

– kill most bacteria, but not Mycobacterium tuberculosis or endospores – safe and easy to use, but inactivated by hard water and soap

Answer 46

• cationic detergents are effective disinfectants

Question 47

– organic molecules with hydrophilic and hydrophobic ends – act as wetting agents and emulsifiers

Answer 47

• detergents

Question 48

• highly reactive molecules • sporicidal and can be used as chemical sterilants • combine with and inactivate nucleic acids and proteins ex. formaldehyde pr glutaraldehyde

Answer 48

aldehydes

Question 49

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

Answer 49

Sterilizing Gases