Chp 7

Question 1

Sepsis

Answer 1

refers to bacterial contamination

Question 2

Asepsis

Answer 2

is the absence of significant contamination

Question 3

Aseptic surgery techniques prevent

Answer 3

the microbial contamination of wounds

Question 4

Sterilization

Answer 4

removing and destroying all microbial life

Question 5

Commercial sterilization

Answer 5

killing C. botulinum endospores from canned goods

Question 6

Disinfection:

Answer 6

destroying harmful microorganisms

Question 7

Antisepsis:

Answer 7

destroying harmful microorganisms from living tissue

Question 8

Degerming

Answer 8

the mechanical removal of microbes from a limited area

Question 9

Sanitization

Answer 9

lowering microbial counts on eating utensils to safe levels

Question 10

Biocide (germicide):

Answer 10

treatments that kill microbes

Question 11

Bacteriostasis:

Answer 11

inhibiting, not killing, microbes

Question 12

(rate of microbial death) Effectiveness of treatment depends on:

Answer 12

1) Number of microbes
2) Environment (organic matter, temperature, biofilms)
3) Time of exposure
4) Microbial characteristics

Question 13

Actions of Microbial Control Agents

Answer 13

1) Alteration of membrane permeability
2) Damage to proteins (enzymes)
3) Damage to nucleic acids

Question 14

Thermal death point (TDP):

Answer 14

lowest temperature at which all cells in a liquid culture are killed in 10 min

Question 15

Thermal death time (TDT):

Answer 15

minimal time for all bacteria in a liquid culture to be killed at a particular temperature

Question 16

what does heat do to enzymes

Answer 16

denatures

Question 17

Decimal reduction time (DRT)

Answer 17

Minutes to kill 90% of a population at a given temperature

Question 18

Moist Heat Sterilization

Answer 18

1) Moist heat denatures proteins
2) Boiling
3) Free-flowing steam

Question 19

Autoclave

Answer 19

• steam under pressure
• 121 C at 15 psi for 15 min
• Kills all organisms and endospores
• Steam must contact the item’s surface

Question 20

Moist Heat Sterilization

Answer 20

Large containers require longer sterilization times

Test strips are used to indicate sterility

Question 21

Pasteurization

Answer 21

reduces spoilage organisms and pathogens

Question 22

Thermoduric

Answer 22

organisms survive

Question 23

Dry Heat Sterilization

Answer 23

Kills by oxidation

• Flaming
• Incineration
• Hot-air sterilization

Question 24

Filtration is the

Answer 24

Passage of substance through a screenlike material

Question 25

filtration is used for

Answer 25

heat-sensitive materials

Question 26

Two types of filters

Answer 26

1) High-efficiency particulate air (HEPA) filters - remove microbes > 0.3 µm 2) Membrane filters - remove microbes > 0.22 µm

Question 27

Physical Methods of Microbial Control

Answer 27

1) Low Temp 2) High Pressure 3) Desiccation 4) osmotic pressure

Question 28

Low temp and microbial control

Answer 28

Low temperature has a bacteriostatic effect Examples - Refrigeration - Deep-freezing - Lyophilization (freeze drying)

Question 29

High pressure and microbial control

Answer 29

denatures proteins

Question 30

Desiccation and microbial control

Answer 30

absence of water prevents metabolism

Question 31

Osmotic pressure and microbial control

Answer 31

Omotic pressure uses salts and sugars to create hypertonic environment; causes plasmolysis

Question 32

Radiation types

Answer 32

Ionizing radiation Non ionizing radiation Microwaves

Question 33

Ionizing radiation

Answer 33

(X rays, gamma rays, electron beams) 1) Ionizes water to create reactive hydroxyl radicals 2) Damages DNA by causing lethal mutations

Question 34

Nonionizing radiation

Answer 34

(UV, 260 nm) Damages DNA by creating thymine dimers

Question 35

Microwaves

Answer 35

kill by heat; not especially antimicrobial

Question 36

Principles of Effective Disinfection

Answer 36

1) Concentration of disinfectant 2) Organic matter 3) pH 4) Time

Question 37

Dilution Tests

Answer 37

1) Metal cylinders are dipped in test bacteria and dried 2) Cylinders are placed in disinfectant for 10 min at 20°C 3) Cylinders are transferred to culture media to determine whether the bacteria survived treatment

Question 38

The Disk-Diffusion Method

Answer 38

1) Evaluates efficacy of chemical agents 2) Filter paper disks are soaked in a chemical and placed on a culture 3) Look for zone of inhibition around disks

Question 39

Phenol and Phenolics

Answer 39

Injure lipids of plasma membranes, causing leakage

Question 40

Bisphenols

Answer 40

1) Contain two phenol groups connected by a bridge 2) Hexachlorophene and triclosan 3) Disrupt plasma membranes

Question 41

Biguanides

Answer 41

1) Chlorhexidine 2) Used in surgical hand scrubs 3) Disrupt plasma membranes

Question 42

Halogens

Answer 42

Iodine | Chlorine

Question 43

Iodine

Answer 43

is a halogen 1) Tincture: solution in aqueous alcohol 2) Iodophor: combined with organic molecules 3) Impairs protein synthesis and alters membranes

Question 44

Chlorine

Answer 44

is a halogen 1) Oxidizing agents; shut down cellular enzyme systems 2) Bleach: hypochlorous acid (HOCl) 3) Chloramine: chlorine + ammonia

Question 45

Alcohols

Answer 45

1) Denature proteins and dissolves lipids 2) No effect on endospores and nonenveloped viruses 3) Ethanol and isopropanol - Require water

Question 46

Heavy Metals and Their Compounds

Answer 46

Oligodynamic action—very small amounts exert antimicrobial activity Denature proteins Ag, Hg, Cu, Zn - Silver nitrate is used to prevent ophthalmia neonatorum - Mercuric chloride prevents mildew in paint - Copper sulfate is an algicide - Zinc chloride is found in mouthwash

Question 47

Chemical Food Preservatives

Answer 47

1) Sulfur dioxide prevents wine spoilage 2) Organic acids - Inhibit metabolism - Sorbic acid, benzoic acid, and calcium propionate prevent molds in acidic foods 3) Nitrites and nitrates prevent endospore germination

Question 48

Antibiotics

Answer 48

Bacteriocins—proteins produced by one bacterium that inhibits another Nisin and natamycin prevent spoilage of cheese

Question 49

Aldehydes inactivate

Answer 49

proteins by cross-linking with functional groups

Question 50

Aldehydes are used

Answer 50

for preserving specimens and in medical equipment examples: -Formaldehyde and ortho-phthalaldehyde -Glutaraldehyde is one of the few liquid chemical sterilizing agents

Question 51

Chemical Sterilization

Answer 51

1) Gaseous sterilants cause alkylation—replacing hydrogen atoms of a chemical group with a free radical 2) Cross-links nucleic acids and proteins 3) Used for heat-sensitive material Ethylene oxide

Question 52

Plasma

Answer 52

1) Fourth state of matter, consisting of electrically excited gas 2) Free radicals destroy microbes 3) Used for tubular instruments

Question 53

Supercritical Fluids

Answer 53

1) CO2 with gaseous and liquid properties | 2) Used for medical implants

Question 54

Peroxygens and Other Forms of Oxygen

Answer 54

1) Oxidizing agents 2) Used for contaminated surfaces and food packaging O3, H2O2, and peracetic acid