Chapter 9: Control of Microbial Growth- Part 1

Question 1

The British Medical Journal stated that British physician ______ _____ “saved more lives by the introduction of his system than all the wars of the 19th century together had sacrificed”

Answer 1

Joseph Lister

Question 2

Lister revolutionized _______ by…..

Answer 2

Surgery

Introducing methods to prevent infection of wounds

Question 3

Whose work was Joseph Lister inspired by and what did it lead him to wonder?

Answer 3

Pasteur (swan-neck flasks), wondered if “minute organisms” might be responsible for infections

Question 4

What did Lister apply directly onto damaged tissues?

Answer 4

Carbolic acid (phenol), helped prevent infections

Question 5

Lister improved methods further by…

Answer 5

Sterilizing instruments and maintaining clean operating environment

Question 6

Lister introduced..

Answer 6

Antiseptics

Question 7

Until the ___ century, patients undergoing even minor surgeries were at great risk of developing…

Answer 7

19th

Fatal infections

Question 8

Why did people often die from infections after surgery before the 19th century?

Answer 8

• Physicians did not know their hands could pass diseases from one patient to the next
• Did not understand airborne microbes could infect open wounds

Question 9

Why can dental surgery be dangerous (example)?

Answer 9

Some of the normal flora in the mouth can move with dental surgery and cause infection in the heart

Question 10

Two types of approaches to control microbial growth

Answer 10

Physical methods

Chemical methods

Question 11

Physical methods of controlling microbial growth

Answer 11

Heat
Irradiation
Filtration
Mechanical (e.g., washing)

Question 12

Chemical methods of controlling microbial growth

Answer 12

Disinfectants

Antibiotics

Question 13

Sterilization

Answer 13

Removing all microbes, “best of the best”

Question 14

Pasteurization

Answer 14

Heat treatment

Question 15

Decontamination

Answer 15

Reduce number of microbes to “safe” level (Wescodyne)

Question 16

Sanitation

Answer 16

Substantially reduce microbe number public health standards (usually what is done in bathrooms)

Question 17

Preservation

Answer 17

Delaying spoilage (usually in terms of food biology)

Question 18

Disinfectants

Answer 18

Used on inanimate objects (fomites)
-Will eliminate most microorganisms
Ex: ammonia, bleach, pines, Lysol

Question 19

Antiseptics

Answer 19

Chemicals applied to body surfaces to help control infection

Ex: iodine, rubbing alcohol, mercurochrome

Question 20

Why is hydrogen peroxide a poor antiseptic?

Answer 20

Our skin has an enzyme called catalase which inactivates the hydrogen peroxide (bubbling means it is not working)

Question 21

Microbial control method depends on what?

Answer 21

Situation and level of control required

Question 22

Places where microbial control is practiced

Answer 22

Daily life, hospitals, microbiology laboratories, food production facilities, water treatment facilities

Question 23

Why don’t we entirely sterilize water?

Answer 23

Some bacteria are helping to clean our water waste and are necessary (which is why you should not put sterilizers down the toilet)

Question 24

Selection of an antimicrobial procedure would look at… (5)

Answer 24

• Type of microorganism
• Number of microbes initially present
• Environmental conditions
• Potential risk of infection
• Composition of the item

Question 25

Type of microorganism

Answer 25

• Heat and chemical resistant
• Bacterial endospores and myobacterium species
• Vegetative cells are susceptible to most disinfectants

Question 26

Number of microbes initially present

Answer 26

“99.9% effective” would still be a lot of bacteria! (Lysol)

Question 27

Environmental conditions

Answer 27

Oil, grease and dirt can potentially inactivate products

Question 28

Critical instruments (Potential risk of infection)

Answer 28

Sharps

Question 29

Semicritical instruments

Answer 29

Mucous membranes

Question 30

Noncritical instruments

Answer 30

Intact skin

Question 31

Composition of item

Answer 31

• Metals are damaged by some disinfectants

- Plastics are damaged by irradiation

Question 32

The most common method of sterilization of sharps is..

Answer 32

Irradiation or autoclave

Question 33

Moist heat techniques

Answer 33

Boiling
Pasteurization
Autoclave
Commercial canning process

Question 34

Boiling kills….

Answer 34

Most bacteria and viruses

Question 35

What is the goal of pasteurization?

Answer 35

Kill as many microorganisms as possible without changing the taste, texture, etc of the food

Question 36

What is pasteurization effective for?

Answer 36

Many food-borne microbes

Question 37

Process of Pasteurization

Answer 37

Heat to 72 degrees C for 15 seconds for most liquids

Question 38

Autoclave

Answer 38

Huge pressure cooker, high pressure increases boiling temp of water, typically reach 120 decrees celsius at 15 psi

Question 39

What type of virus would be most likely to survive the high temperatures?

Answer 39

Non-enveloped

Question 40

The most serious threat in the commercial canning process is…

Answer 40

Clostridium botulinum endospores because they are anaerobic, but when placed in a can they germinate and produce endospores

Question 41

What do canning facilities use?

Answer 41

Retorts which are large autoclaves

Question 42

What do retorts do?

Answer 42

Prevent endospores from germinating inside the can, thus preventing botulism toxin production

Question 43

In the commercial canning process, how do we know the retorts have worked?

Answer 43

A “dummy can” that has a monitor on the inside is included with every batch

Question 44

Dry heat

Answer 44

Heating items to 200 degrees celsius or more

Question 45

You have used Wecodyne on a paper towel on your laboratory bench and have removed most of the microorganisms from it making it “safe”. You would say that it has been

Answer 45

Decontaminated

Question 46

Chlorine bleach is an example of a(n)

Answer 46

Disinfectant