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Exam 3 Micro Lecture: Ch 7 Microbial Control

front 1

___________ is rapidly becoming the most popular team in the hospital. Who does it include?

back 1

Infection control team
Pharmacists all the way down to housekeeping

front 2

nosocomial infections

back 2

acquired in the hospital

front 3

What is the worst method for washing one’s hands?

back 3

Waterless, alcohol based hand wipes

The alcohol in the hand wipes dries out fast and you need a 70% alcohol solution to disinfect things so they do not work well and people do not really rub with friction to get stuff off with those.

front 4

What actually removes the bacteria while washing your hands?

back 4

The friction of you moving your hands back and forth.

front 5

Sterilization

back 5

The destruction or removal of all microbial life, including endospores.

front 6

Disinfectant

back 6

Any treatment used on inanimate objects to kill or inhibit the growth of microorganisms; removing pathogens. Doesn't kill spores.

front 7

Sanitization

back 7

The removal of microorganisms from eating utensils and food preparation areas.

front 8

Decontaminate

back 8

to make (an object or area) safe for unprotected personnel by removing, neutralizing, or destroying any harmful substance, as radioactive material or poisonous gas

front 9

We wish to control microbes under these two conditions

back 9

1. Destroy and reduce the transmission of pathogens

2. Reduce or eliminate contaminating microbes from food, water, special areas, etc.

front 10

De-germ

back 10

the removal of microorganisms from an area

front 11

Septic

back 11

infected with a toxic or pathogenic organism in the blood or tissue, especially in respiratory or urinary tracts

front 12

Aseptic

back 12

free from pathogenic organisms (especially on skin) that cause disease or infection

free from contamination

front 13

2 main chemical disinfecting agents that kill microorganisms or inhibit their growth

back 13

1. - cides
2. - static

front 14

- cides

back 14

agents which kill microbes

front 15

-static

back 15

Stops microbes from growing but do not kill them. The microbes are there and if you take the treatment away, they can resume growth.

front 16

Germicides

back 16

kill microorganisms and viruses, but not necessarily endospores

front 17

Alcohol kills microbes best at what %?

back 17

70%

front 18

Endospore

back 18

protective structure to endure environmental stress

front 19

Most resistant organism to being killed

back 19

prions

front 20

Microbes are considered to be dead when ______

back 20

they are unable to reproduce in conditions that normally support their reproduction

front 21

How do microbes die?

back 21

When you spray down a counter top, they're not all killed immediately.

Adding disinfectant in stationary phase makes death phase start the exponential decrease. This decrease will differ depending on the microbe.

When a population has been greatly reduced, the rate of death may slow due to survival of resistant organisms.

front 22

exponential decrease

back 22

The population will be reduced by the same fraction in each time interval

front 23

D-value

back 23

Decimal reduction value. Also called D process.

Time required to kill 90% of the microbial population under specific conditions at that particular dose.

the dose of the disinfectant and how long you have to expose it for your # of microbes to be reduced by a power of 10.

front 24

1 D-process reduces the number of microbes by ______

back 24

one exponent

front 25

Use-dilution Test

back 25

Where you set up microbes in liquid culture and add to that culture different concentrations of your test disinfectant. Determine MIC or MBC.

front 26

MIC

back 26

Minimum inhibitory concentration. What is the minimum dose we need to have to prevent microbial growth> Doesn’t tell you one particular aspect: did we kill the microbes or did we just stop them from growing?

front 27

MBC

back 27

After MIC, the second step you can do as an add on is take the cultures that don’t look like they have microbes growing in them and dilute them into fresh media so its been diluted down to where the disinfectant is not going to work and we will see if the microbe grows back. Then we can determine the concentration we need to kill the microbes. Not just make sure it slows down and stops growing but gets killed.

front 28

Dilution factor

back 28

how much can you dilute it?

front 29

5 disinfectant considerations

back 29

1. Dilution factor
2. Time of exposure
3. Target microbes
4. Cost
5. Surfaces of interest

front 30

Time of exposure

back 30

How long does it take for you to kill off the microbes? If you have to wipe down the counter for 30 minutes, its not useful.

front 31

Target of microbes

back 31

Making sure it kills the microbes you care about.

front 32

Surfaces of interest

back 32

Making sure it doesn’t degrade or have nasty effects on to whatever surface.

front 33

Disk-Diffusion Method

back 33

We use the size of that zone of inhibition to compare how effective different disinfectants are on killing any one microbe.

front 34

2 chemical control agents

back 34

1. gasses
2. liquids

front 35

2 gas control agents

back 35

1. sterilization
2. disinfection

front 36

3 liquid control agents

back 36

1. antisepsis
2. disinfection
3. sterilization

front 37

3 methods of mechanical control

back 37

1. sanitation
2. degermination
3. filtration sterilization

front 38

2 types of filtration sterlization

back 38

1. air
2. liquids

front 39

2 physical control agents

back 39

1. heat
2. raditation

front 40

2 types of radiation control agents

back 40

1. ionizing
2. non ionizing

front 41

2 types of heat control

back 41

1. dry
2. moist

front 42

ionizing radiation

back 42

uses x-rays and gamma rays to sterilize

Destroys bacterial endospores

not always effective against viruses

front 43

How does ionizing radiation work?

back 43

strips electrons from atoms

Penetrates deep into objects

Causes damage to DNA and potentially to plasma membrane

Also indirect damage by producing reactive molecules

front 44

what two byproducts does ionizing radiation produce?

back 44

1. Superoxide free radicals
2. hydroxyl free radicals

front 45

nonionizing radiation

back 45

uses UV rays to disinfect

Damages DNA causing thymine dimers

Generates free radicals

front 46

2 forms of dry heat control

back 46

1. incineration
2. dry oven

front 47

2 types of moist heat control

back 47

1. sterilization (steam under pressure)
2. disinfection (boiling water, hot water, pasteurization)

front 48

2 physical removal agents

back 48

1. surficants
2. soaps and detergents

front 49

surficant

back 49

breaks water surface tension

front 50

detergent

back 50

Emulsifies all hydrophobic lipids and fats so that you can physically remove the microbes from hands.

front 51

Ignatz Semmelweis

back 51

"savior of mothers"

The guy who figured out that washing hands is so important. Austrian surgeon in late 1800s. Delivered babies too. Before we had gloves they would go and do dissections of cadavers between giving birth. Friend of his got stuck with a scalpel and died and noticed that he died of what the pregnant women died of.

Figured out that if you wash your hands and instruments in a harsh chlorine bath (undiluted) then his patients survived. He became head of hospital and insisted everyone did this. Old surgical stink guys (see few slides later) did not like this and got offended by this saying I am a gentleman, I am clean. But he showed them the data.

front 52

Joseph Lister

back 52

He wore to surgery:
“an old blue frock-coat for operation, which he had previously worn in the dissecting room; stiff and glazed with blood”

Developed the first spray disinfectant: Carbolic Acid - phenol - will dissolve your skin. We do not use it anymore.

front 53

4 methods using heat and moisture

back 53

1. autoclave - true sterilization
2. canning
3. pasteurization
4. boiling

front 54

Pressurized steam

back 54

Autoclave used to sterilize using pressurized steam

use saturated steam under pressure to reach temperatures above boiling

front 55

Autoclave achieves sterilization at ___°C and ___psi in ____minutes

back 55

121
15
15

front 56

Pasteurization

Why developed?
What is it?
Does it sterilize?
What is it used for with our food?

back 56

Pasteur developed to avoid spoilage of wine

Controlled heating at temperatures well below boiling

Does not sterilize but significantly reduces organisms

Used to increase shelf life of food

front 57

flash pasteurization

What is it used for?

back 57

(High temperature short-term – HTST)

72°C for 15 seconds then rapid cooling (milk)

82°C for 20 seconds (ice cream)

front 58

ultra high temperature pasteurization

What is it used for?

back 58

(UHT) sterilization

140 to 150°C for 1 to 3 seconds

Used for single serving cream containers and boxed juices

The problem is that the higher the temp, the more likely you are to break down the chemical components of that food and alter the taste

front 59

dry heat

back 59

Not as effective as moist heat

Sterilization requires longer times and higher temperatures

200°C for 1.5 hours vs. 121°C for 15 minutes

oxidizes cell constituents and denatures proteins

front 60

Incineration

back 60

Oxidizes cell to ashes

Used to destroy medical waste and animal carcasses

Flaming laboratory inoculation loop incinerates organism

front 61

radiation

back 61

electromagnetic radiation

Energy released from waves

Shorter wavelength, higher frequency = more energy

Range of wavelengths is electromagnetic spectrum

Radiation can be ionizing or non-ionizing

front 62

Why is UV radiation limited to surface sterilization?

back 62

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

front 63

irradiation

back 63

99.9-99.99% effective against E. coli on leafy greens

Breaks down cell walls a bit though

Meats, poultry, some shellfish and spices are also approved

#1 way to sterilize plastics

front 64

ionizing radiation is used for sterilizing what?

back 64

Gamma radiation used for sterilization and pasteurization of antibiotics, hormones, sutures, plastic disposable supplies, and food

front 65

nonionizing radiation is used for what?

back 65

Used to destroy microbes in air, drinking water and surfaces

front 66

main sterilizing gas

back 66

Ethylene Oxide

front 67

How does sterilizing gas work?

back 67

Destroys microbes including endospores and viruses

Combines with and inactivates proteins

front 68

What is sterilizing gas used to sterilize?

back 68

Used to sterilize heat- or moisture- sensitive materials

front 69

what is the down side to using sterilizing gas?

back 69

Mutagenic and potentially carcinogenic

Extensive aeration of sterilized materials necessary

front 70

What are the vital targets for chemical microbial killing? (5)

back 70

1. Proteins (enzymes) - target its function, denature
2. Ribosomes - target its function
3. DNA - mutate it
4. Plasma membrane - poke holes in it, lysis
5. Cell wall - poke holes in it

front 71

3 main chemical methods of killing

back 71

1. disruption of plasma membrane
2. protein denaturation
3. oxidation

front 72

carbolic acid

back 72

Phenol

First used by Lister ca. 1870

disruption of plasma membrane

front 73

How do phenols work?

back 73

Act by denaturing proteins and disrupting cell membranes

effective in presence of organic material and long lasting

Kill most vegetative cells (5-10% kill Mycobacterium)

Not reliable against all viruses

Things that poke holes in membranes and trigger cell lysis are things that contain phenol in them. Effective against most bacteria but not mycobacterium and spores. But lots of disinfectants have phenol type compounds in them. It can poke holes in plasma membranes and can poke holes in membranes of our cells.

front 74

Examples of phenols

back 74

lysol
triclosan

front 75

4 main types of protein denaturation

back 75

1. alcohols
2. phenolics
3. heavy metals
4. quaternary ammonia

front 76

How does alcohol work as a chemical method of killing microbes?

back 76

Solutions of 60% - 80% isopropyl or ethyl alcohol kill vegetative bacteria and fungi. effective against mycobacteria.

Not effective against endospores and some naked viruses

Coagulates proteins and essential enzymes and damages lipid membranes

Commonly used as antiseptic and disinfectant

front 77

2 limitations to using alcohol as a chemical method of killing microbes

back 77

1. Evaporates quickly, limiting contact time
2. May damage material such as rubber and some plastics

front 78

How do heavy metals work as a chemical method of killing microbes?

back 78

e.g. Ions of mercury, silver, arsenic, zinc, and copper

Compounds combine with enzymes and proteins interfering with function

High concentrations of many metals toxic to human tissue

Silver still used as a disinfectant

Creams containing silver sulfadiazine used to prevent secondary infections

Also available on bandages for wound care

front 79

How does ammonia work as a chemical method of killing microbes?

back 79

It denatures proteins. Common in hospitals as detergent and denaturant. Pseudomonas bacteria causes infections in burn patients and in contact lens wearers. This bacteria has developed resistance against ammonia compounds.

front 80

2 main types of oxidation used in chemical microbial killing

back 80

1. halogens (iodine and chlorine)
2. hydrogen peroxide

front 81

How does hydrogen peroxide function as a chemical microbial killing agent?

back 81

Powerful oxidizing agent

Effectiveness depends on surface being treated

Living tissue produces catalase enzyme which breaks down hydrogen peroxide

More effective on inanimate objects

Useful as disinfectant

Leaves no residue

Doesn’t damage most materials

Hot solutions commonly used in food industry

Vapor-phase is more effective and can be used as sterilant

Readily biodegradable

front 82

oxidation

back 82

transfers electrons from one to another to break down physical components

front 83

How halogens work at killing microbes

back 83

Oxidize proteins and other cell components

front 84

tincture

back 84

alcoholic solution

front 85

idophore

back 85

carrier molecule

front 86

How is iodine used as a chemical microbial killer?

back 86

Kills vegetative cells but not reliable with endospores

Used as a skin antiseptic in tincture or iodophore

effective with mycobacteria

front 87

How is chlorine used as a chemical microbial killer?

back 87

Important disinfectant

Works through oxidation

Used to disinfect water supplies and swimming pools, dairy and food industries

Effective household disinfectant

Caustic to skin and mucous membranes

Destroys vegetative bacteria and fungi, but not spores

Can react with organic matter to form carcinogenic compounds

front 88

8 points to consider in choosing a chemical microbial killer

back 88

1. Highly effective - Fast acting, even when dilute, have a broad range of activity over various environmental conditions, soluble and active in both water and oils

2. Activity in presence of organic material - Many germicides inactivated in presence of organic matter

3. Toxicity

4. Compatibility with material being treated - Liquids cannot be used on electrical equipment

5. Residue - Residues neither toxic or corrosive, odorless, non-staining

6. Cost and availability

7. Storage

8. Environmental risk