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Microbiology > Sterilization, Disinfection, and Antisepsis > Flashcards

Sterilization, Disinfection, and Antisepsis Flashcards

1
Q

Cross-infection:

A

Transmission of infectious agents among

patients and staff in a clinical environment

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2
Q

Cross-infection control:

A

Management strategies for risk control

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3
Q

Cross-infection risks in dentistry
Possible sources of infection in the dental care setting:
(4)

A 
Patients with infectious disease
Patients in the prodromal or
convalescent stage of infection
Healthy (or asymptomatic) carriers
of disease-causing organisms
Environmental sources: airborne
organisms or biofilms in waterlines
or on equipment or instruments
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4
Q

Universal precautions:

A

All patients are treated as though

they are a potential source of infectious pathogens.

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5
Q

Airborne Routes

Examples of dust-borne routes:

A

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

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6
Q

Airborne Routes

Examples of aerosol routes:

A

large droplets (classified as contact)
droplet nuclei
sources: speaking, sneezing, all intraoral procedures.
Massive increase when using ultrasonic scaling, air-rotor,
air/water syringe.

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7
Q

Prevention of aerosol transmission (2)

A
  1. Elimination or limitation of organisms at source

2. Interruption of transmission

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8
Q

Contact Routes

person-to-person:

A

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

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9
Q

Contact Routes
equipment:
(3)

A

dental instruments
chairs
impression materials

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10
Q

skipped
Contact Routes
prevention :

A 
sterilization of instruments
use of disposals
disinfection of dental materials
environmental hygiene
defining zones in the dental operatory
disposal of infected waste
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11
Q 
Contact Routes (continued)
Fluids
A

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

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12
Q

Parenteral Spread of Cross-Infection
Sources: (3)
Inoculation: via (4)

A

blood, saliva, and secretions

eye, skin breach, mucous membrane, sharps injury

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13
Q

skipped
Parenteral Spread of Cross-Infection
prevention:

A

training in use and disposal of sharps, hepatitis B

vaccination, wearing gloves, dressing wounds

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14
Q

• sterilization

A

– destruction of all microbial forms (including bacterial spores)

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15
Q

• disinfection

2

A

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

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16
Q

– disinfectants

3

A
  • agents, usually chemical, used for disinfection
  • usually used on inanimate objects
  • high-level, intermediate-level, low-level
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17
Q

• antisepsis

2

A

– Inhibition or elimination of microbes on living tissue

– antiseptics

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18
Q

– antiseptics

A

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

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19
Q

• sanitization

A

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

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20
Q

Antimicrobial agents

3

A

• agents that kill microorganisms or inhibit
their growth
• -cidal agents kill
• -static agents inhibit growth

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21
Q

The Pattern of Microbial Death

3

A

• 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

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22
Q

Once the population has
been greatly reduced the
rate of killing may slow due
to

A

resistant individuals

23
Q

Conditions Influencing the Effectiveness of
Antimicrobial Agent Activity
(6)

A

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

24
Q

The Use of Physical Methods in
Control
(4)

A
  • heat
  • low temperatures
  • filtration
  • radiation
25
Q

Heat
• moist heat
(2)

A

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

26
Q

Heat
• dry heat sterilization
(2)

A

– less effective, requiring higher temperatures and
longer exposure times
– oxidizes cell constituents and denatures proteins

27
Q

Measuring heat-killing efficiency

• thermal death time (TDT)

A

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

28
Q

Measuring heat-killing efficiency

• decimal reduction time (D or D value)

A

– time required to kill 90% of microorganisms or spores

in a sample at a specific temperature

29
Q

• Z value

A

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

30
Q

Autoclaves

2

A

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

31
Q

Moist heat
• pasteurization
(2)

A

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

32
Q

Pasteurization of milk

2

A

•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

33
Q

Low Temperatures
• freezing
(2)

A

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

34
Q

Low Temperatures

• refrigeration

A

– slows microbial growth and reproduction

35
Q

Filtration

2

A

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

36
Q

Filtering liquids

• depth filters

A

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

37
Q

Filtering liquids

• membrane filters

A

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

38
Q

Filtering air (2)

A

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

39
Q

Radiation

• ultraviolet (UV) radiation

A

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

40
Q

Radiation
• ionizing radiation
(3)

A

– 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

41
Q

Phenolics

4

A

• 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

42
Q

Alcohols

4

A

• 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)

43
Q

Halogens

contain (4)

A

fluorine, chlorine, bromine, iodine

44
Q

Halogens
• Iodine
(5)

A

-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)

45
Q

Halogens
• Chlorine
(4)

A

-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

46
Q

Heavy Metals

3

A

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

47
Q

Quaternary Ammonium
Compounds
• detergents (2)

A

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

48
Q

Quaternary Ammonium
cationic detergents are effective disinfectants
(2)

A

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

49
Q

Aldehydes (3)

A

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

50
Q

Sterilizing Gases (3)

A
  • used to sterilize heat-sensitive materials
  • microbicidal and sporicidal
  • combine with and inactivate proteins
51
Q

Category: Critical
Level:
Risk:
Objects:

A 
Heat Sterilization 
Very high 
Touch bone or penetrate tissue;
blood present (scalpels, forceps,
scalers, probes, implants)
52
Q

Category: Semi-Critical
Level:
Risk:
Objects:

A

Sterilization, High-level disinfection
Moderate
Touch mucous membrane but not penetrate;
no blood, (mirrors, burnishers, amalgam carriers, etc.)

53
Q

Category: Non-Critical
Level:
Risk:
Objects:

A

Intermediate level
Low
Unbroken skin contact;
no blood; (masks, clothing. Blood pressure cuffs)

54
Q

Category: Environmental surfaces
Level:
Risk:
Objects:

A 
Low level disinfection; sanitation
Minimal
No direct patient contact,
no blood; (door knobs, floors, walls, counters,
mops and other housekeeping equipment)

Microbiology (42 decks)

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