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Microbio > Lecture 11 > Flashcards

Lecture 11 Flashcards

1
Q

Clean is

A

foreign material has been removed either manually or mechanically
For surgery - an object or surface has been disinfected and not knowingly exposed to pathogens

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2
Q

Aseptic means

A

free from pathogenic organisms

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3
Q

Sterile means

A

No living microorganisms are present
Includes spores

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4
Q

Sterilize means

A

complete destruction or removal of all microorganisms and their pathogenic products (endotoxins and exotoxins)

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5
Q

Contaminated means

A

presence of unwanted microorganisms

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6
Q

Disinfect means

A

destruction or removal of vegetative microorganisms but not bacterial endospores
Refers to inanimate objects

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7
Q

Disinfectant means

A

chemical applied to inanimate objects to disinfect

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8
Q

Antiseptic means

A

chemical applied to living tissue to disinfect

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9
Q

Sterilization is

A

Sterilization is the process of destroying all microorganisms and their pathogenic products
Does NOT refer to prions and may not destroy all plasmids
Used to maintain asepsis - both to prevent contamination and to destroy contaminants

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10
Q

4 main methods of sterilization

A

Sterilization by heat (moist heat or dry heat)​
Chemical sterilization​
Ultra-filtration​
Ionizing radiation​

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11
Q

Steam sterilization is

A

An item is subjected to moist heat, at a predetermined temperature, under a predetermined pressure, for a predetermined length of time
Microbes are destroyed by coagulation of protein, also damages nucleic acids, etc.​
Destroys spores ​
Destroys prions​

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12
Q

Autoclave is

A

Placing steam under very high pressure to increase the temperature to approx. 120°C
Pressure does not increase the killing effect but causes more heat to be required for water to boil
Typical pressures in an autoclave are 20 psi (pounds per square inch)
Can range from table-top models to large full-room units​

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13
Q

Components of an autoclave

A

Airtight door with bolting mechanism to hold in pressure​
Metal chamber for holding materials to be autoclaved​
Steam source​
Steam exhaust​
Pressure and temperature gauges ​

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14
Q

How long does an autoclave take and what can be used

A

It takes about 20 minutes for an object to be sterilized
Can be used to sterilize liquids, wrapped, and unwrapped materials​

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15
Q

Liquid sterilization is

A

Glutaraldehyde and formaldehyde
Toxic and irritating
Antimicrobial

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16
Q

Cold sterilization is

A

Soaking instruments in disinfecting solutions (chlorhexidine or glutaraldehyde)​
Used only for minor procedures or equipment that cannot tolerate other sterilization methods​
Must be rinsed thoroughly with sterile water under aseptic conditions (sterile gloves)​

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17
Q

Gas sterilization is

A

Plasma Sterilization – Hydrogen Peroxide
Safer for environment and personnel than ethylene oxide​

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18
Q

When not to use gas sterilization

A

Linen​
Wood/paper​
Endoscopes​
Certain plastics​
Liquids​
This method cannot penetrate the walls of instruments so the lumen will remain contaminated

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19
Q

Antiseptics and disinfectants work by

A

Damaging the cell membranes ​
Interfering with or damaging proteins ​
Damaging DNA and/or RNA​

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20
Q

How is the strength of a disinfectant measured

A

The strength of a disinfectant is measured by a value called the Phenol Coefficient or Co-efficient of Disinfectant​
The higher this number, the better its ability to kill microbes​

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21
Q

Why are chemicals limited when it comes to doing both spores and viruses

A

Chemicals that work by destroying cell membranes are limited in their ability to kill spores and certain viruses
Spores do not have accessible cell membranes
Only some viruses have membranes

22
Q

Ethanol is

A

Most commonly used at 70% v/v dilution ​
Kills all vegetative cells, including Mycobacterium​
Does not destroy spores, kills some viruses​
Dissolves lipids, denatures proteins, does not damage nucleic acids​
There must be contact time, so apply alcohol and allow to evaporate
Has decreased efficacy at higher temperatures due to faster evaporation​
Ethanol is NOT effective at 95-100% due to rapid evaporation​

22
Q

Characteristics of the ideal disinfectant

A

Has a good coefficient of disinfection – good killing action at low concentration
Broad spectrum - Vegetative bacteria and fungi; bacterial endospores and fungal spores; enveloped and non-enveloped viruses
Stable - Can be stored for long periods of time without losing effectiveness - Can store at room temp, in the presence of light and air
Homogeneous - Uniform in composition; every application acts the same
Soluble – soluble in water → makes it more effective to use
Non-toxic to animals and people
Non-corrosive, non-bleaching, non-staining, not flammable
Works at room temperature
High penetrance of biofilms and fat
Detergent ability - Uniform in composition; every application acts the same
Is not neutralized by organic material that may be present
Ease of use
Affordable and readily available
Deodorizing

23
Q

Ethanol advantages

A

Cuts through fat and lipids
Inexpensive, readily available
Can use on skin, on inanimate surfaces, for soaking → both a disinfectant and an antiseptic
Comes in a hand gel format that includes surgical-strength hand cleaners

24
Q

Disadvantages of ethanol

A

Will cause cooling when applied to skin
Can be absorbed causing alcohol intoxication - especially in small animals and pediatrics
Flammable, explosive
Damages plastics and rubber

25
Q

Isopropyl alcohol is

A

2-propanol​
Used at 70% v/v dilution (aka rubbing alcohol)​
As effective as ethanol, especially if fortified with iodine or another disinfectant​
Cheaper and more easily obtainable than ethanol

26
Q

Quaternary ammonium compounds are and work by

A

Commonly used disinfectant
Disrupts cell membranes and denatures proteins​

27
Q

Range of activity for Quaternary Ammonium Compounds

A

Broad spectrum against bacteria
Effective at destroying enveloped viruses ​

28
Q

What are the older generations of Quaternary Ammonium Compounds not effective against

A

Non-enveloped viruses​
Some Pseudomonas resistance ​
Mycobacterium​
Spores​

29
Q

Quaternary Ammonium Compounds advantages

A

Stable, dissolves easily in water
Odorless, does not stain, not corrosive
Effective in pus, blood, feces
Inexpensive

30
Q

Quaternary Ammonium Compounds disadvantages

A

Can cause slight injury to tissue
Should never be mixed with soaps (will decrease efficacy)
Decreased activity in hard water
Older generations require long contact times (10-20 min)

31
Q

Three types of oxidizing agents

A

Hydrogen peroxide (PeroxigardTM)
Hypochlorites
Potassium peroxymonosulfate (Virkon®)

32
Q

Hydrogen peroxide is

A

(H2O2)-Containing Compounds​
Very commonly used​
Hydrogen peroxide forms free-oxygen radicals ​
damage cell membranes, mitochondria, and other cell components​
Common products include: Peroxigard®, Virox®, Percept®, Accel®

33
Q

Hydrogen peroxide activity

A

Broad spectrum​
NON-ENVELOPED VIRUSES​
Can destroy spores at very high concentrations​
If concentratio

34
Q

Hydrogen Peroxide Advantages

A

Decomposes to water and oxygen
Inexpensive, easy to use aqueous solution
Can be vaporized and used for “gas sterilization”
Objects are placed in a chamber and gassed with a hydrogen peroxide compound
Good for glass, metals, certain equipment

35
Q

Hydrogen Peroxide disadvantages

A

Decomposes in the presence of light, metals, oxygen
New formulations are stable for months in storage

36
Q

how do hypochlorites work

A

Chlorine-containing agents​
Most common → Sodium hypochlorite (Bleach)​
Denatures protein​
The chlorine combines with water to release hypochlorous acid (HOCl) ​
During the reaction, any surrounding cysteine residues and S-S bonds are destroyed​
Broad spectrum including bacteria, fungi, spores and all types of viruses​
Acts within 30 min; spores may take hours

37
Q

Cautions to take with hypochlorites

A

Concentrated solutions will rapidly release chlorine gas
Never mix with acid → will produce toxic chlorine gas
Never combine with the Quats→ will produce toxic chloramine gas
Caustic effects to skin and mucus membranes, especially at higher concentrations

38
Q

Sodium hypochlorite is

A

Concentrated sodium hypochlorite is 20% w/v​
Household bleach is 5.25% w/v sodium hypochlorite​
To use as a disinfectant, use a 10% solution of household bleach ​
Corrosive → must be rinsed afterwards ​
Be careful of fumes when using concentrated sodium hypochlorite ​
Area must be well ventilated ​
Avoid spills

39
Q

Potassium Peroxymonosulfate (Virkon®) is and works on

A

Oxidizing agent with detergent action
Oxidizes sulfur bonds in proteins and enzymes disrupting the function of the cell membrane causing rupturing of the cell
Broad spectrum bacteria, fungi, most viruses
Not spores

40
Q

How and when to use Potassium Peroxymonosulfate (Virkon®)

A

Comes as a tablet that makes a 1% solution in water
7-day shelf-life once made
Requires 10 min of contact time followed by rinsing
Disinfecting hard surfaces, including food bowls, cages, kennels
Can also use as aerosol if concerned about air contamination
Low toxicity but avoid direct skin use

41
Q

Why are phenols not used in a clinic

A
  • Infrequently used in the veterinary clinic as they can cause toxicities in cats
42
Q

Chlorhexidine Gluconate​ is

A

Antiseptic that is related to the Quats​
Mild, low toxicity, rapid acting, poor absorption​ by GI system

43
Q

Chlorhexidine Gluconate​ uses salts how

A

Complex organic molecules that dissociates into a positively charged salt​
This salt binds to and disrupts negative charges associated with bacteria cell walls​
Low concentrations: Static ​
High concentrations: Cidal ​

44
Q

Chlorhexidine Gluconate​ works agaisnt

A

Broad-spectrum against bacteria, yeast and some viruses ​
No action on spores​
Antiseptic of choice for MRSA

45
Q

Chlorhexidine Gluconate​ strengths available

A

Chlorhexidine is available in strengths ranging from 0.05% to 4% ​
Higher concentrations will cause tissue damage and delayed wound healing​
Intact skin can withstand a higher concentration than wounds​

46
Q

Chlorhexidine Gluconate​ two formulas

A

Aqueous formulas ​
-Safe for use around eyes and for flushing of wounds​
Solutions containing alcohol
-NOT safe around the eyes and will cause damage to wound and healing tissue ​

47
Q

Iodine is and can be used for

A

Broad spectrum bactericidal ​
Used at a 2 - 2.5% solution​
Used for cleaning cuts, wounds, surgical prep​
Apply in single coat to skin and allow to air dry
AVOID eye contact​
Do NOT allow to pool under patient on a surgery mat ​
Will cause burns if prolonged contact with solution​

48
Q

How is iodine purchased

A

Can be purchased as​
Aqueous solution ​
A “tincture”​
2.0 - 2.5% iodine in 70% ethanol
More effective because can cut through lipid​

49
Q

Iodophors are

A

Iodine that is loosely bound to a detergent (such as povidine) that releases it slowly AND cuts through organic matter
Prolonged effect after applied to skin
Not irritating to the skin; but can have mild hypersensitivity and will discolor skin
Povidine-iodine is most common (Betadine, Losan)
Surgical scrubs (esp. in LA), teat dips

Microbio (11 decks)

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