Control Of Microbes

Question 1

What is sterilization

Answer 1

Killing or removal of all viable organisms including endospores
Endospores are very resistant

Question 2

What is disinfection

Answer 2

Fomites or inanimate objects that can harbor microorganisms

Question 3

What is sanitization

Answer 3

This lowers numbers to where it is safer
Decreasing viral or microbial numbers
Doesn’t eliminate endospores
Doesn’t get rid of everything

Question 4

What is antisepsis

Answer 4

Used on live tissue to disinfect
Can’t use same concentration that you would on inanimate objects
Things in living tissue take longer to work and you don’t want to kill living tissue

Question 5

What are antimicrobial agents

Answer 5

They will kill or inhibit microbes but aren’t the same thing as antibiotics

Question 6

What is chemotherapy

Answer 6

Use of chemicals to kill or inhibit growth of microorganisms within host tissue

Question 7

What is cidal

Answer 7

Kills microorganisms
Penicillin is an example because it stops bacteria

Question 8

What is static

Answer 8

Inhibits microorganisms
Slow growth rate of proteins in microorganisms
Inhibits protein synthesis in bacteria
Hopefully slows protein synthesis long enough to lead to death

Question 9

When does population death of microbes occur

Answer 9

Exponentially rather than right away

Question 10

What is the lag phase

Answer 10

Period of adjustment

Question 11

What is the log phase

Answer 11

When microbes are actively reproducing

Question 12

What is the stationary phase

Answer 12

Growth rate and death rate are equal

Question 13

What is the death phase

Answer 13

Occurs exponentially
Slow process from beginning to end

Question 14

What is the D value

Answer 14

Measure of agents killing efficiency
Decimal reduction time or time to kill 90 percent of the microbes
Must make sure persister cells are dead because they could regain ability to reproduce and cause infection

Question 15

What is a deciding factor in if a disinfectant will work

Answer 15

The abundance of microorganisms

Question 16

How does filtration work in mechanical control of microorganisms

Answer 16

Relies on physical barriers
Reduces microbial population or sterilizes solutions of heat sensitive materials by removing microorganisms
Can be used to reduce microbial population in the air

Question 17

When filtering liquids why are membrane filters important

Answer 17

They stop microorganisms from passing but allow liquids to move through
They have a defined pore size that removes microorganisms primarily by physical screening

Question 18

How could toy filter air to avoid microorganisms

Answer 18

Surgical masks
Cotton plugs on culture vessels
High efficiency particulate air filters

Question 19

How do physical control methods avoid microorganisms

Answer 19

They alter the microbes to make them non viable
Can use heat or radiation

Question 20

How does moist heat work

Answer 20

Degrades nucleic acids, denatures proteins, and disrupts membranes
Quicker or more efficient to use
Boiling doesn’t destroy microorganisms and endospores it just reduces numbers

Question 21

How does steam sterilization work

Answer 21

Carried out above 100 degrees Celsius which requires saturated steam under pressure
Uses an autoclave and if effective against all microorganisms included endopspores!!!

Question 22

What does pasteurization do

Answer 22

Kills pathogens to slow spoilage by reducing total load or organisms present
High temperature short time which means 161 degrees for at least 15 seconds

Question 23

What is dry heat sterilization

Answer 23

Less effective than moist heat and requires longer exposure time with higher temps
Will denature proteins

Question 24

What is ultraviolet radiation

Answer 24

Wavelength of 260 nm is most bactericidal
Causes thymine dimers and prevents replication and transcription
Limited to surface sterilization and has been used for water treatment

Question 25

What is ionizing radiation

Answer 25

Gamma radiation penetrates deep into object Destroys bacterial endospores but not always effective against viruses Used for sterilization and pasteurization of antibiotics, hormones, and disposable supplies as well as food

Question 26

Ask Annabelle

Answer 26

Slide 21

Question 27

What are phenolics used for

Answer 27

Laboratory and hospital disinfectants Act but denaturing proteins and disrupting cell membranes

Question 28

How do alcohols work

Answer 28

Inactivate some viruses Most common are ethanol and isopropanol Most widely used disinfectants and antiseptics Bactericidal and fungicidal but not sporicidal

Question 29

What are halogens

Answer 29

Important antimicrobial agents Fluorine, chlorine, bromine, iodine, and astatine

Question 30

How does iodine work

Answer 30

Oxidizes cell constituents and iodinates proteins Skin antiseptic Can kill spores at high concentrations Skin damage, staining, and allergies could be a problem

Question 31

What is an iodophore

Answer 31

Iodine complexed with organic carrier Released slowly to minimize skin burns

Question 32

What does chlorine do

Answer 32

Oxidizes cell constituents Disinfects water supplies and destroys vegetative bacteria and fungi Chlorine gas is sporicidal Can react with organic matter to become carcinogenic

Question 33

What are heavy metals

Answer 33

Effective but usually toxic Combined with and inactivate proteins, can also precipitate proteins

Question 34

What are quaternary ammonium compounds

Answer 34

Detergents that have antimicrobial activity Amphipathic organic cleansing agents disrupt membranes

Question 35

Are cationic or anionic detergents effective disinfectants

Answer 35

Cationic They kill most bacteria but not M tuberculosis or endospores Inactivated by hard water and soap

Question 36

How are aldehydes used

Answer 36

Commonly used as formaldehyde and glutaraldehyde Highly reactive Combine with new inactivate nucleic acids and proteins

Question 37

How does glutaraldehyde work specifically

Answer 37

It hooks with proteins so it changes their structure and allows them to not function properly

Question 38

What do sterilizing gases do

Answer 38

Sterilize heat sensitive materials They are microbidical and sporicidal Inactivate dna and proteins

Question 39

How is ethylene oxide sterilization carried out

Answer 39

Using equipment that is similar to the autoclave

Question 40

True or false: smaller populations take longer to kill than larger ones

Answer 40

False, larger populations take longer to

Question 41

Do higher or lower concentrations microbes more effectively

Answer 41

Higher concentrations but the relationship between concentration and microbe death is not linear More is not always better because some disinfectants can eat through material or evaporate too quickly

Question 42

Is gram negative or positive harder to get rid of

Answer 42

Gram negative because they have an outer membrane

Question 43

How does duration of exposure relate to microbial death

Answer 43

Longer exposure means more organisms killed Usually ten minute time frame

Question 44

How does temperature relate to microbial death

Answer 44

Higher temps usually increase killing It speeds up molecular motion and increases protein denaturing

Question 45

What aspects impact effectiveness of disinfectants

Answer 45

Ph, viscosity, concentration or organic matter Organisms in biofilms are less susceptible to antimicrobial agents

Question 46

What does fluorescent pseudomonas do that’s important

Answer 46

Use microorganisms in rhizoids to convert nitrogen and phosphorus into usable forms the plant can use

Question 47

What is entomopathogenic fungi

Answer 47

Insect specific pathogenic fungi used to control mosquitos Female mosquitoes will mate with males that cannot reproduce and kill eggs

Question 48

What is wolbachia

Answer 48

Insect specific bacteria Being developed to control mosquitos Makes males sterile and releases them into the environment