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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: l

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:

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
dust vs aerosol borne?
examples?
when is aerosol increased?

A

Examples of dust-borne routes:
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

Examples of aerosol routes:
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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6
Q

Prevention of aerosol transmission

A
  1. Elimination or limitation of organisms at source

2. Interruption of transmission

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7
Q

Contact Routes, preventions

A

person-to-person:
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

equipment: 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

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

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8
Q

Parenteral Spread of Cross-Infection
sources
innoculation
prevention

A

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

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9
Q

sterilization

A

– destruction of all microbial forms (including bacterial spores)

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10
Q

disinfection
agents of this? mainly?
used on?
levels?

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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11
Q

antisepsis

A

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

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12
Q

sanitization

A

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

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13
Q

Antimicrobial agents

A

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

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14
Q

The Pattern of Microbial Death

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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15
Q

rate of microbial killing with time

A

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

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16
Q

Conditions Influencing the Effectiveness of Antimicrobial Agent Activity

A
  • population size
  • population composition
  • concentration or intensity of an antimicrobial agent
  • duration of exposure
  • temperature
  • local environment (e.g. pH, viscosity, etc.)
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17
Q

The Use of Physical Methods in Control

A
  • heat
  • low temperatures
  • filtration
  • radiation
18
Q

• moist heat

A

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

19
Q

• dry heat sterilization

A

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

20
Q

Measuring heat-killing efficiency, values?

A

• thermal death time (TDT)
– shortest time needed to kill all microorganisms in a suspension at a specific temperature and under defined conditions

• decimal reduction time (D or D value)
– time required to kill 90% of microorganisms or spores in a sample at a specific temperature

21
Q

Z value

A

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

22
Q

Autoclaves

A

type of moist heat
– used to kill endospores efficiently
– use saturated steam under pressure to reach temperatures above boiling

23
Q

Moist heat- pasteurization, milk?

A

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

Pasteurization of milk
•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

24
Q

Low Temperatures (freezing and refrigeration)

A

• freezing
– stops microbial reproduction due to lack of liquid water
– some microorganisms killed by ice crystal disruption of cell membranes
• refrigeration
– slows microbial growth and reproduction

25
Q

Filtration

A
  • reduces microbial population or sterilizes solutions of heat-sensitive materials by removing microorganisms
  • also used to reduce microbial populations in air
26
Q

Filtering liquids, types of filters?

A

• depth filters
– thick fibrous or granular filters that remove microorganisms by physical screening, entrapment, and/or adsorption
• membrane filters
– porous membranes with defined pore sizes that remove microorganisms primarily by physical screening

27
Q

Filtering air tools

A
  • surgical masks

* high-efficiency particulate air (HEPA) filters

28
Q

Radiation types

A

UV and ionizing

29
Q

ultraviolet (UV) radiation

A

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

30
Q

ionizing radiation

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

31
Q

Phenolics
commonly used where?
mechanism?
problems?

A

phenol, hexochlorophene
• 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

32
Q

Alcohols
work on?
mechanism?
concentration?

A

ethanol, isopropanol
• 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)

33
Q

Halogens

A

contain fluorine, chlorine, bromine, iodine

34
Q 
Iodine
primary use?
mechanism? 
high concentrations? 
issues? 
iodophores?
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)
35
Q 
Chlorine
mechanism? 
important where? 
can/cannot destroy? 
carcinogen?
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
36
Q

Heavy Metals

A
  • e.g., ions of mercury, silver, arsenic, zinc, and copper
  • effective but usually toxic
  • combine with and inactivate proteins; may also precipitate proteins
37
Q

Quaternary Ammonium

Compounds

A

cetylpyridium chloride, benzalkonium chloride
• 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

38
Q

Aldehydes
reactivity?
spores?
mechanism?

A
  • highly reactive molecules
  • sporicidal and can be used as chemical sterilants
  • combine with and inactivate nucleic acids and proteins
39
Q

Sterilizing Gases
used for?
-cidal towards?
mechanism?

A

ethlyene oxide, betaproprionelactone
• used to sterilize heat-sensitive materials
• microbicidal and sporicidal
• combine with and inactivate proteins

40
Q

Spaulding Inanimate Objects Classification

A

microbiology (42 decks)

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