Chapter 7 - Control of Microbial Growth

Question 1

Sterilization

Answer 1

removal of all microbial life (includes endospores!)

Question 2

Commercial Sterilization

Answer 2

killing C. botulinum endospores before being placed on grocery shelves

Question 3

Disinfection

Answer 3

removal of vegetative/non-endospore forming pathogens

Question 4

Antisepsis

Answer 4

destruction of vegetative pathogens or living tissue

Question 5

Degerming

Answer 5

removal of microbes from a limited area (usually skin)

Question 6

Sanitization

Answer 6

lowers the microbial count on eating and drinking utensils

Question 7

Ignaz Semmelweis

Answer 7

hand-washing

Question 8

Joseph Lister

Answer 8

aseptic surgery-disinfectant

Question 9

Mycobacteria have what kind of cell wall?

Answer 9

waxy and lipid

Question 10

What part of the protozoa are resistant to chemical disinfection?

Answer 10

cyst

Question 11

Gram ____ bacteria are more resistant.

Answer 11

negative

Question 12

_____ are resistant to normal autoclaving and disinfection.

Answer 12

prions

Question 13

What are 5 factors that influence the effectiveness of antimicrobials?

Answer 13

1) number of microbes
2) certain characteristics
3) environmental conditions
4) time of exposure
5) action of antimicrobial

Question 14

What are 2 actions of antimicrobials?

Answer 14

1) changing of the permeability of the plasma membrane

2) damaging the protein/nucleic acid

Question 15

Prions

Answer 15

infections proteins

Question 16

More resistant microbes include

Answer 16

prions, endospores, mycobacteria, cysts of protozoa, vegetative protozoa

Question 17

Less resistant microbes include

Answer 17

viruses with lipid envelopes, gram-positive bacteria, viruses without envelopes, fungi, gram-negative bacteria

Question 18

Autoclave

Answer 18

sterilization using moist heat (higher than boiling point) in the form of steam by autoclaving at 121 degrees at 15 psi for 15 minutes
*preferred form of sterilization, its moist heat denatures proteins

Question 19

Boiling

Answer 19

sterilization that kills most vegetative pathogens, viruses, and fungi along with their spores (most of the time)

Question 20

Direct Flaming and Incinerators

Answer 20

sterilization by dry heat which kills by oxidation (inoculating loop)

Question 21

Hot Oven

Answer 21

sterilization by dry heat which sterilized metal, glass, and plastic items (heat-sensitive items)

Question 22

Ethylene Oxide

Answer 22

sterilization of culture media (virology), vaccines, IVs/antibiotics, solutions, and hospital equipment

Question 23

Filtration

Answer 23

sterilization by separating bacteria from suspending liquids

Question 24

HEPA (high efficiency particulate air)

Answer 24

sterilization used for airborne microbes such as in the mycobateriology lab, burn unit, operating room, and rooms of AIDs patients

Question 25

Ionizing Radiation

Answer 25

sterilization that destructs DNA by means of x-rays. gamma rays, and electron beams

Question 26

Nonionizing Radiation

Answer 26

sterilization that damages DNA by means of UV rays

Question 27

Desiccation

Answer 27

sterilization that disrupts the of metabolism by removing water from microbes (used for food preservation)

Question 28

High Pressure

Answer 28

sterilization that alters the molecular structure of proteins and carbohydrates but preserves nutrient values (used for fruit juices)

Question 29

Osmotic Pressure

Answer 29

sterilization that uses plasmolysis for food preservation

Question 30

Organic Acids

Answer 30

sterilization that causes metabolic inhibition used to control molds and some bacteria in food

Question 31

Nitrates/Nitrites (meat products)

Answer 31

sterilization that inhibits certain iron-containing enzymes of anaerobes that prevents the growth of C. botulinum

Question 32

Refrigeration

Answer 32

sterilization that decreases chemical reactions

Question 33

Deep-Freezing

Answer 33

sterilization that decreases chemical reactions (-50 - -95 degrees C)

Question 34

Lyophilization

Answer 34

sterilization that decreases chemical reactions that leaves a poweder-like residue for preservation

Question 35

Pasteurization

Answer 35

denatures proteins by using high heat for a short amount of time (reduces spoilage) (doesn't sterilize)

Question 36

Soap and Water

Answer 36

mechanical removal of microbes through scrubbing

Question 37

Cationic Detergents (Quats)

Answer 37

antiseptics for utensils that inhibit enzymes, denature proteins, and disrupt plasma membranes (most effective against gram positives)

Question 38

Alcohol

Answer 38

degerming (antiseptic) or disinfecting (thermometers) that denatures proteins and disrupts plasma proteins (not effective again endospores)

Question 39

Halogens

Answer 39

oxidizing agents such as tincture and iodophors that inhibit protein function

Question 40

Biguanides (Chlorohexidine)

Answer 40

skin disinfectants (surgical hand scrubbing) that disrupt plasma membranes

Question 41

Phenolics

Answer 41

disinfectants such as lysol and amply used on inert surfaces to denature enzymes and disrupt plasma membranes

Question 42

Bisphenols

Answer 42

disinfectant hand soaps and antiseptics (hexachlorophene) that might disrupt plasma membranes

Question 43

Aldehydes

Answer 43

gluteraldehydes and formaldehyde disinfect medical equipment by denaturing proteins

Question 44

Heavy Metals

Answer 44

antiseptics such as copper sulfate and silver nitrate that denature entire proteins

Question 45

Hydrogen Peroxide

Answer 45

disinfectants and antiseptics that act as oxidizing agents to clean contaminated surfaces

Question 46

How does the filter paper disk diffusion method work?

Answer 46

1) paper disk soaked w/ disinfectant 2) place disk on inoculated agar plate 3) disinfectant diffuses out of disk into agar during incubation 4) clear zone of inhabitation indicates effectiveness of disinfectant * larger the zone, the more sensitive the microbe is

Question 47

All the following achieve sterilization EXCEPT: a. boiling b. autoclave c. incineration d. pasteurization e. radiation

Answer 47

D) pasteurization

Question 48

What is the mode of action for phenols? a. dissolve lipids b. denature proteins c. oxidizing agents d. disruption of the plasma membrane e. both b and d

Answer 48

E) both B and D

Question 49

If a microbiologist wants to use a gas to sterilize hospital items, which of the following methods is appropriate? a. radiation b. ethylene oxide c. filtration d. pasteurization e. all of the above

Answer 49

B) ethylene oxide

Question 50

The term disinfection refers to: a. removal of all forms of microbial life b. lowering microbial counts on eating and drinking utensils c. destruction of vegetative pathogens on living tissue d. removal of microbes from a limited area, such as skin e. destruction of vegetative pathogens on inert surfaces.

Answer 50

E) destruction of vegetative pathogens on inert surfaces

Question 51

Which of these is most resistant to chemical antimicrobials? a. endospores b. prions c. gram-negative bacteria d. Mycobacterium e. enveloped viruses

Answer 51

B) prions

Question 52

Which method is preferred for sterilizing heat-labile culture media? a. autoclave b. hot air oven c. boiling d. filtration e. glutaraldehyde

Answer 52

B) hot air oven

Question 53

Which of these factors influences the effectiveness of antimicrobial treatments? a. microbial load b. microbes in surface biofilms c. presence of feces in the material d. exposure time e. all of the above

Answer 53

E) all of the above

Question 54

antiseptic

Answer 54

used on live surfaces

Question 55

disinfectant

Answer 55

used on inert surfaces