Chapter 7 - Control of Microbial Growth Flashcards Preview

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Flashcards in Chapter 7 - Control of Microbial Growth Deck (55):
1

Sterilization

removal of all microbial life (includes endospores!)

2

Commercial Sterilization

killing C. botulinum endospores before being placed on grocery shelves

3

Disinfection

removal of vegetative/non-endospore forming pathogens

4

Antisepsis

destruction of vegetative pathogens or living tissue

5

Degerming

removal of microbes from a limited area (usually skin)

6

Sanitization

lowers the microbial count on eating and drinking utensils

7

Ignaz Semmelweis

hand-washing

8

Joseph Lister

aseptic surgery-disinfectant

9

Mycobacteria have what kind of cell wall?

waxy and lipid

10

What part of the protozoa are resistant to chemical disinfection?

cyst

11

Gram ____ bacteria are more resistant.

negative

12

_____ are resistant to normal autoclaving and disinfection.

prions

13

What are 5 factors that influence the effectiveness of antimicrobials?

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

14

What are 2 actions of antimicrobials?

1) changing of the permeability of the plasma membrane
2) damaging the protein/nucleic acid

15

Prions

infections proteins

16

More resistant microbes include

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

17

Less resistant microbes include

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

18

Autoclave

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

19

Boiling

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

20

Direct Flaming and Incinerators

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

21

Hot Oven

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

22

Ethylene Oxide

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

23

Filtration

sterilization by separating bacteria from suspending liquids

24

HEPA (high efficiency particulate air)

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

25

Ionizing Radiation

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

26

Nonionizing Radiation

sterilization that damages DNA by means of UV rays

27

Desiccation

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

28

High Pressure

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

29

Osmotic Pressure

sterilization that uses plasmolysis for food preservation

30

Organic Acids

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

31

Nitrates/Nitrites (meat products)

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

32

Refrigeration

sterilization that decreases chemical reactions

33

Deep-Freezing

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

34

Lyophilization

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

35

Pasteurization

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

36

Soap and Water

mechanical removal of microbes through scrubbing

37

Cationic Detergents (Quats)

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

38

Alcohol

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

39

Halogens

oxidizing agents such as tincture and iodophors that inhibit protein function

40

Biguanides (Chlorohexidine)

skin disinfectants (surgical hand scrubbing) that disrupt plasma membranes

41

Phenolics

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

42

Bisphenols

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

43

Aldehydes

gluteraldehydes and formaldehyde disinfect medical equipment by denaturing proteins

44

Heavy Metals

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

45

Hydrogen Peroxide

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

46

How does the filter paper disk diffusion method work?

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

47

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

D) pasteurization

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

E) both B and D

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

B) ethylene oxide

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.

E) destruction of vegetative pathogens on inert surfaces

51

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

B) prions

52

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

B) hot air oven

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

E) all of the above

54

antiseptic

used on live surfaces

55

disinfectant

used on inert surfaces