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MBIO 3000 > Disinfection > Flashcards

Disinfection Flashcards

1
Q

Why do we disinfect?

A
  • to get rid of unwanted pathogenic microorganisms

to eliminate or at least reduce exposure risk
- medical waste treatment
- spill cleanup
- minimization of nosocomial infections
- routine surface decontamination

to eliminate contamination risk
- preparation of microbiology media and supplies
- prep of pharmaceutical production supplies and equipment
prep of food- surface sanitization
prep of work are for cleanliness- critical tasks

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2
Q

What are the 5F’s?

A

food
fingers
flies
feces
fomites
(water, air, vehicles, transported blood and tissues)

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3
Q

sterilization

A

act or process physical or chemical that destroys or eliminates all forms of life especially microorganisms- highest level

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4
Q

disinfectant

A

an agent usually chemical that inactivates viruses or kills vegetative microbes but not nescecarily resistant forms such as spores

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5
Q

antiseptic

A

a substance that prevents or arrests the growth or action of microbes either by inhibiting their activity or by destroying them- living tissue

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6
Q

decontamination

A

disinfection or sterilization of contaminated articles to make them suitable for use
- minimizing risk of transmission/ contamination

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7
Q

sanitizer

A

an agent that reduces the number of vegetative bacteria only
- doesn’t kill everything on hands but reduces to safe number

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8
Q

cide

A

kills- determined by specific testing

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9
Q

bacetricide

A

= germicide
destroys vegetative bacteria only

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10
Q

sporocide

A

destroys bacterial spores

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11
Q

fungicide

A

destroys fungal spores

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12
Q

tuberculocide

A

destroys M. tuberculosis

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13
Q

virucide

A

destroys specific viruses

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14
Q

static

A

prohibits growth may not kill

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15
Q

bacetriostatic

A

prevents growth of veg bacteria
- but doesnt kill whats on surface
lots of antibiotics have their affect

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16
Q

tuberculostatic

A

prohibits growth of Mycobacterium tuberculosis

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17
Q

Resistance to disinfectants

A
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18
Q

What is the mode of action of chlorine

A
  1. saponification of fatty acids
  2. neutralization of amino acids
  3. chloramination of amino acids
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19
Q

Who was Ignaz Semmelweis

A

pioneered physician handwashing with calcium hypochlorite

20
Q

chlorine

A
  • available as liquid powder or table form
  • household bleach usually 5-6% Na hypochlorite
  • in use dillutions depend on application and amount of organic material present
  • leaves stains

working solutions should be prepared fresh within 24 hours and kept in light protected containers
stock liquids lose Cl concentration over time
corrosive; neutralized by organic material
clo2 gas used in mail center against anthrax

21
Q

What is organic material?

A

ex- someone bleeding out in the hospital the blood is a mixture of things; microorganisms saliva and can effect how effective disinfectants are

22
Q

what is chlorine effective against?

A

veg bacteria
mycobacteria
viruses
fungal spores
some sporicidal activity

23
Q

How is chlorine reduced by organic material?

A

more organic material the less effective
would need to increase concentration to reduce the number of bacteria

24
Q

How does iodine work?

A

oxidizes amino acids, fatty acids, nucleotide’s etc; causing denaturation

25
Q
A
26
Q

Iodine

A

available as an aqueous solution, tincture (solution in alcohol) and iodophor (iodine complexed with carrier molecule to increase solubility and provide sustained release of the halogen eg- povidone iodine

27
Q

What is iodine effective against?

A
  • enveloped (lipid containing) viruses
    veg bacteria, fungi
    variable activity against mycobacteria, non enveloped viruses and bacterial spores
28
Q

list some of the disadvantages of iodine

A

staining treated items corrosiveness and neutralization by organic material
wescodyne povidone- iodine

29
Q

alcohols

A
  • ethyl alcohol (ethanol, ETOH)
    -isopropyl alchohol (isopropanol, IPA)
  • flammable
30
Q

What is the most effective concentration of alcohol and why?

A

70% in water is most effective concentration
b/c needs h20 to enter membranes and h20 isnt as volatile won’t evaporate quickly

31
Q

what is alcohol effective against? not effective?

A

effective against: enveloped viruses veg bacteria longer contact time (10mins) required for any activity against fungi and mycobacteria

variable against non enveloped viruses

no activity against bacterial spores

longer contact times difficult to achieve due to loss by evaporation

32
Q

phenolics

A

used in combo with detergents

one of 1st disinfectants to be used by surgeons

vesphene LpH are examples

33
Q

What are phenolics effective against? not effective against?

A

effective against
- enveloped viruses
- vegetative bacteria

variable activity against fungo and mycobacteria depending on product

limited activity against non enveloped viruses

no activity against bacterial spores

34
Q

list some of the disadvantages of phenolics

A

toxicity
neutralization by hard water
puget unpleasant smell

35
Q

list some of the advantages of phenolics

A

not easily neutralized by organic material
non corrosive

36
Q

Quaternary ammonium compounds

A

quats have innate detergent action but may be inactivated in the presence of some soaps or soap residues

odorless colorless non irritating and deodorizing

roccal germex zephiran coverage plus microchem

37
Q

What are QACS effective against? not effective against?

A

effective vs gram + bacteria
limited activity vs enveloped viruses fungi and gram - bacteria
effectiveness reduced by organic material

38
Q

glutaraldehyde

A
  • 2-4% aqueous solution often with activator
  • use requires adequate ventilation
  • activated product has limited shelf life
  • controversial product because of adverse health effects including mucous membrane irritation contact dermatitis occupational asthma
  • cidex taken off the UK market May 2002
39
Q

formaldehyde

A

supplied as solid paraformaldehyde (flakes or tablets) or as liquid formalin (37% in water with 100 ml/l of methanol stabilizer

disinfectant use is typically 4%

less susceptible to inactivation by organic material

corrosive caustic irritant carcinogen

can be neutralized with ammonium bicarbonate

40
Q

What is formaldehyde effective against? not effective against?

A

broad spectrum of activity against all classes of microorganisms

41
Q

hydrogen peroxide

A

available as a concentrated 37% solution in water (6% in-use solutions)

vapor phase hydrogen perioxide is good volume disinfectant 35-37% solution is converted to vapor phase by heat

leave no residue breaks down to water AND O2

incompatible with aluminum copper zinc brass natural rubber and some plastics

42
Q

What is hydrogen peroxide effective against? not effective against?

A

veg bacteria
mycobacteria
fungi
viruses and spores

43
Q

chlorhexidine

A

available as 2-4% solution of chlorhexidine gluconate (a biguanide) in a detergent base (used undiluted as as concentrated alcohol based solutions requiring dilution prior to use

alcoholic solutions show superior activity to aqueous solutions

generally sued as a antiseptic (skin disinfectant and hand wash)

44
Q

What is chlorhexidine effective against?

A

enveloped viruses and veg bacteria
limited activity against fungi mycobacteria non enveloped viruses
no sporicidal activity

45
Q

the phenol coefficent

A

highest dilution of the test solution divided by the highest dilution of phenol that gives no growth of bacteria culture under standard conditions

ex:
at 10 minutes a disinfectant exhibited no bacterial growth at a dilution of 1in 500
phenol exhibited no bacterial growth at 10 minutes at 1 in 95
phenol coefficient of the disinfectant is 500+95=5.26 or 5.36 x greater than phenol

46
Q

factors influencing efficacy

A
  1. surface- topography
    - whether we decon a stainless steel safety cabinet vs bricks
    - the surface can absorb the disinfectant which effects how it works
  2. temp
    - somethings that effective at 2.5 celcius might not be at 4
  3. relative humidity
    - how much vapor pressure is present in the air
  4. water hardness
    - more minerals in the water could decrease effectiveness of disinfectant
  5. organic load
    - ex cough is a mixture of proteins, virus etc
  6. concentration
    - if you use something to dilute it wont effectiveley clean area
  7. contact time
    - how long its on surface for
47
Q
A

MBIO 3000 (9 decks)

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