Ph 162A Lec 12: Environmental Control Of Microorganisms

Front 1

Why do we want to control microorganism?

Back 1

1. Public Health--disease potential
2. Food Spoilage-- Industrial (food contamination) and preservation
3. Person spoilage (mummification--using natural extracts to delay the decay processes)

Front 2

[definition and terms]

Sterilization

Back 2

removing/killing all living forms

Front 3

Disinfection

Back 3

reducing the number of organisms to a level where they pose no danger of disease

note: Disinfection means 6 log number reduction in bacteria (99.9999%) and 4 log reduction of viruses (99.99)

Front 4

Antiseptic

Back 4

chemical agent which can be safely applied externally to the host but destroy/inhibits microorganism. May not be effective for spores.

Front 5

disinfectant

Back 5

chemical agent applied to inanimate objects to destroy/inhibit. May not be effective for spores

Front 6

sanitizer

Back 6

chemical agent used on food-handling equipment/eating utensils to to reduce the numbers of microorganisms

Front 7

bacteriostatic

Back 7

inhibit the growth or microorganisms

***bacteriostatic-- do not kill spore b/c a lot of gram positive organisms have spores

Front 8

Bactericidal

Back 8

kills vegetative state of microorganism, may not effects spors

Front 9

Viricide

Back 9

agent that inactivates viruses

Front 10

fungicide

Back 10

agent that kills fungi

Front 11

sporicide

Back 11

agent that kills bacterial endospores and fungal spores

Front 12

germicide

Back 12

agent of rapid destruction of microorganisms

Front 13

[antimicrobial effects: 3 principles]

Three principles of antimicrobial effects (that shows the product is working well against microorganism)

Back 13

1. A defined proportion of organisms die in a given time interval
2. the smaller the number of organisms to start with the less time needed to remove them (sterility)
3. microorganisms differ in their susceptibility to antimicrobial agents
**the diff. physiological state of the organism will dictate how well the mechanism will work.

Front 14

[bacterial growth curve]

Gives the 4 states of the baterial growth curve

Back 14

**graph pg 122

1. LAG: You introduce them into the new environment with nutrients, and it will take them some time to build up their proper enzyme systems and get their metabolism working.
2. LOG: They begin to divide, and if they are log-based, they are dividing based on a logarithmic rate.
3. Stationary: In the immediate environment, the cells will use up the nutrients available to them when the number of cells reproducing matches the number of cells dying off. This is called the stationary phase. 4. Death: And then you have a death rate. This is after the nutrients have been used up. The microorganism will produce toxic by-products that are toxic to themselves as colony. Mostly, there will be a drop in pH. A spike in pH can also happen.

Front 15

Which is the best state to hit the organism with a bacteriostatic agent?

Back 15

LOG state---> inhibit them when they are still active

Front 16

[Heat Killing]

define thermal death point

Back 16

this is the lowest temperature require to kill all organisms w/in a suspension in 10 minutes

Front 17

Thermal death time

Back 17

the minimum time required to kill all microbes while keeping the temperature constant

note: it's important-- you want the lowest temperature to insure safety, w/o killing the product over time

Front 18

decimal reduction time

Back 18

this is the time required to reduce the microbes by 90%

Front 19

[Antimicrobial Chemical Agents]

what are the 7 things that are important about chemical agents?

Back 19

1. Potency
2. time
3. temperature (some are temperature-dependent)
4. pH
5. concentration (how much are you going to use)
3. type of organism
4. physiological state of organism (what kind of environment does it live or can't do well in)

Front 20

The important thing about chemical agents is the ____

Back 20

potency

Front 21

The first determinant of potency is ____ and the second is ____.

Back 21

1. dose
2. time

Front 22

[selecting a disinfectant]

What are the six things an ideal disinfectant should do/have?

Back 22

1. be fast acting even in the presence of organic substance
2. be effective against all types of infectious agents w/out destroying tissues or acting as a poison if ingested
3. Easily penetrates material to be disinfected w/out damaging the material
4. Easy to prepare and maintains stability when exposed to light
5. inexpensive and easy to obtain and use
6. pleasant ordor

Front 23

[mechanisms of action] There are four basic categories of disinfectant. Disinfectant against ____, ____, _____, and _____

Back 23

1. proteins
2. cell membranes
3. other cell components
4. inactivation of viruses

Front 24

Give the mechanism of the agent/product against:

protein

Back 24

**Affected by denaturation-- alteration of protein structure. This is done by hydrolysis, which changes the structure.

Front 25

Give the mechanism of the agent/product against:

cell membranes

Back 25

**Hydrolysis-- and this is w/ a surfactant (cell membrane is primarily lipid, surfactant (detergents and wetting agents) can dissolve the lipid)

--typically use with other agents to help penetrate the target

Front 26

Give the mechanism of the agent/product against:

Other cell components ( e.g nucleic acids)

Back 26

**this is done by hydrolysis-- break down DNA or RNA

**intercalation
**pathway inhibition-- by things like lactic and propionic acids ( negative feedback onto the organisms)

Front 27

Give the mechanism of the agent/product against:

inactivation of viruses

Back 27

**target the capsid or capsomere--rendering them making them incapable of infecting the host cell

**denature the protein coating
** Chemical mutagens--alter their DNA and RNA

Front 28

[chemical Agents: Soaps and Detergents]

Action of Soaps and detergents

Back 28

Surfactants: dissolves lipids, disrupt membranes, denature proteins

**lower surface tension

Front 29

Give examples of components use in soap/surfactants

Back 29

1. alkali in soap can kill gram positive organisms; some viruses
2. Quaternary Ammonium Compounds

Front 30

[Chemical agents: Acid and Alkali]

Action

Back 30

1. acid or alkali conditions can hydrolyze vital enzymes
2. lower pH (acid) may inhibit fermentation

Front 31

Examples of acid and alkali

Back 31

1. soaps are alkali
2. organic acids used in food preservation (lactic and propionic acids in bread)
3. benzoic acid in soft drinks and condiments

Front 32

[Chemical agents: Heavy Metals]

Action

Back 32

**Oligodynamic action = small concentration big effect.
---> high affinity of proteins and metallic ions--> the ions accumulate w/in the cell and bind to essential proteins and the proteins precipitate out

Front 33

examples of heavy metals

Back 33

mercury (Hg), Silver (Ag), Copper (Cu)-- control algae, Selenium (Se)

Front 34

[Chemical agents: Halogens]

action

Back 34

Oxidation of various compounds

Front 35

example of halogens

Back 35

**iodine and chlorine

Front 36

CHLORINE and CHLORINATED COMPOUNDS:

the compound of action is _____

Back 36

hypochlorous acid (HClO)

**HCIO---> HCl + O becomes a strong oxidizer

Front 37

It is important to get this superoxide, which is _____

Back 37

pH dependent (6.5-7) where it is most stable

Front 38

Chlorine works against

Back 38

bacteria, spores, cysts, viruses, dependent upon concentration and contact time (CT values)

Front 39

Chlorine when mixed w/ small organic molecules form

Back 39

carcinogenic trihalomethanes (THM's)

notes:
**this form in water w/ organics and free chlorine.
**cancerous in animal
**alternative is to use chloramine (but requires greater concentration, CT

Front 40

_______ chlorine is most effective for Legionnaire's disease

Back 40

Free chlorine

note: problem! free chlorine is a very good oxidizing agent-- it will chew up not only organic material but metal as well.

Front 41

[Chemical agents: Alcohol]

Action

Back 41

**alcohols and water precipitate proteins-- most effective at 70%
**solvent for lipids---damages membranes

Front 42

example of alcohol

Back 42

ethanol and isopropyl alcohol

Front 43

Alcohols are effective against

Back 43

vegetative forms, not spore

Front 44

Is Methanol effective?

Back 44

no it is toxic and not as effective

Front 45

[chemical agents: Phenols]

Phenols are know as ____

Back 45

carbolic acid

Front 46

Phenols:

Action

Back 46

disrupt cell membranes, denatures proteins and inactivates enzymes

Front 47

[Chemical agent: oxidizing agents]

Hydrogen peroxide:
Action

Back 47

**Hydrogen peroxide (H2O2)-- breaks down water and superoxide (O2), which is very potent and used for killing anaerobes
--note: strict anaerobes cannot survive in the presence of oxygen and they have no way of detoxifying oxygen

Front 48

[Chemical agent: oxidizing agents]

Potassium permanganate:
action

Back 48

Used on skin, utensils, and in water

note: it is so potent that it can be used to break down organic material (pink color)

Front 49

[Chemical agent: oxidizing agents]

Ozone (O3): action

Back 49

water treatment, surface contact

note: very potent in knocking potent organisms in water, but doesn't last long

Front 50

[chemical agent: Alkylating agents]

Action

Back 50

**target proteins and nucleic acids
**These are things like formaldehyde and propriolactone used in vaccine preparation; do not damage antigen required to illicit an immune response.

Front 51

[chemical agent: Alkylating agents]

Ethylene oxide: use on...

Back 51

used on things that would be destroyed by heat

note: extraordinary toxic; indiscriminate in what it react with

Front 52

[Chemical agent: Dyes]

Action

Back 52

disrupts nucleic acid, cell synthesis, cell walls. May inhibit cellular oxidation process

Front 53

what are other agents that we use to control microorganism?

Back 53

*Natural products (herb thyme)
*Sulfites and sulfur dioxide
*nitrates and nitrites (toxic to us)
*Molasses, sugars, salts

Front 54

[Physical Agents]

What are some physical agents we used to control microbes? (4)

Back 54

1. Dry heat, moist heat and pasteurization
2. Low temperature control
3. Radiation
4. Filtration

Front 55

Dry Heat:

1. How does it works?
2. Where do you use it on?

Back 55

1. Penetrates slowly, oxidizes organic material
2. used on primarily on glass, metal, powders, oils; open flames used in micro labs

Front 56

Moist Heat:

1. Action
2. where do you use it?

Back 56

1. High penetration and effectiveness; moist heat under pressure is best
--under pressure, temperature > 100 degrees celcius
--kill even the most resistant spores

2. use on metallic items, heat stable media and reagents, glassware

Front 57

Pasteurization:

1. Action
2. where do you use it?

Back 57

notes: Loius Pasterus discovered pasteurization (1800s)

1. flash heating 71.6 C for 15 secs
--ultra high temperature (UTH)-- to avoid cooked flavor

2. used in milk, beer, wine, etc.

Front 58

2. Low temperature control

What are the four methods for low temp. control?

Back 58

1. Refrigeration
2. Freezing
3. Drying
4. Freeze-drying
--lyophilization. small ice crystals are formed and then the vaccum removes the water directly into the gas phase

Front 59

3. Radiation: Ultraviolet Light (40-390 nm)

1. action
2. use in ____

Back 59

1. permanently damages. cells do have repair mechanisms for minor damage control.
--effective on viruses.

2. low penetrating capabilities, good for sterilizing air and some surfaces
--use in sewage treatment in place of chlorine

Front 60

Radiation: Ionizing Radiation

1. Action
2. use in ___

Back 60

1. Gamma rays and X-rays. Highly energetic.-- lethal to bacteria can inactivate viruses

2. used to sterilized heat sensitive materials: plastics, some foods (diary, meats and fruit)
--medical waste and sewage treatment

Front 61

Radiation: Microwave Radiation

1. Action

Back 61

1. Match wavelengths of energy levels in water. the water heats up and moist heat is created

Front 62

Radiation: Strong Visible light

1. Action
2. use in____

Back 62

1, flashes of really bright light which damages proteins and nucleic acides

2. can only be used for surfaces and not for anything that needs penetration

Front 63

[Physical agents: Filtration]

1. action
2. where is it used in?

Back 63

1. Physically removing cells w/ a sieve
--sterilization by filtration requires very small pore sizes

2. high-efficiency particulate air (HEPA) filter (O.3 micrometer)-- Used in "clean" labs and in "hot" labs