Ch 7 Controlling the Growth of Microbes

Question 1

sterilization

Answer 1

• remove or destroy all forms of microbial life

Question 2

disinfection

Answer 2

reduce number of vegetative pathogens to level that is safe

Question 3

antisepsis

Answer 3

disinfection of the skin or other tissues

Question 4

degerming

Answer 4

physical removal of harmful microbes

Question 5

sanitization

Answer 5

lowering microbial levels to “safe” levels

Question 6

sepsis

Answer 6

bacterial contamination

Question 7

asepsis

Answer 7

absence of contamination

Question 8

the control of microbes is

Answer 8

• not used to treat disease but reduces transmission and limits exposure
• may involve physically removing microbes from surfaces
• may be microbicidal (killing) or microbistatic (inhibits)

Question 9

Physical means of control of bacteria

Answer 9

• heat
• cold
• desiccation
• radiation
• filtration

Question 10

chemical means of control of bacteria

Answer 10

• targets: cell wall, cell membrane, proteins, cellular processess

Question 11

heat

Answer 11

• dry heat
• weat heat: boiling water, steam
• pasteurization: batch, flash, UHT, UHS

Question 12

autoclave

Answer 12

15 psi, 121 C, 15 min

Question 13

dry heat sterilization

Answer 13

• flaming and incineration

- hot air baking (171 c/1hr or 160 c /2 hrs)

Question 14

cold and desiccation

Answer 14

• cold temperatures (below 20 C) retards growth
• freezing causes cell damage by ice crystal formation
• removal of water retards growth: drying or salt preservation

Question 15

radation

Answer 15

• ionizing radiation

- non-ionizing radiation

Question 16

ionizing radiation

Answer 16

• forms ions on variety of cellular chemicals

- x-rays, gamma rays

Question 17

non-ionizing radiation

Answer 17

• uv radiation: damages DNA

Question 18

filtration

Answer 18

• exclusion filtation (filtering out microbes through holes of a particular size): membrane filters
• HEPA (air pushes outmicrobes and air is recirculted)

Question 19

Chemicals

Answer 19

• halogens
• Phenol
• alcohols
• peroxides
• heavy metals
• aldehydes
• quaternary ammonium
• detergents

Question 20

henols

Answer 20

denature proteins and disrupt membranes

Question 21

alcohols

Answer 21

• denature proteins and disrupt membranes

Question 22

halogens

Answer 22

• oxidize enzymes and disrupt membranes
• iodine: iodophors: iodine-containing organics
• cholrine: hyprochlorite

Question 23

peroxides

Answer 23

• oxidizing agents

Question 24

heavy metals

Answer 24

• Hg, Ag, Cu, Ar

- interfere with protein function

Question 25

Aldehydees

Answer 25

• H-C=O
• denature proteins
• effective at low concetration

Question 26

detergents (surfactants)

Answer 26

• reduce surface tension of water
• dissolve lipids
• quaternary ammonia compounds

Question 27

quaternary ammonia compounds

Answer 27

• zepheron

- allows remove of non-polar and organic material

Question 28

Gases

Answer 28

• ethylene oxide, propylene oxide
• denature proteins and DNA
• highly toxic, flammable

Question 29

variables of application

Answer 29

• concetration
• timing
• temperature
• pH
• Nature of material

Question 30

disinfection

Answer 30

• removal of harmful microbes usually from inanimate surface

Question 31

antisepsis

Answer 31

• removal of potential pathogens from living tissue

Question 32

most resistant to least resistant

Answer 32

Prions
endospore
mycobactera
cysts of protozoa
vegetative protozoa
gram negative
fungi (fungal spore)
viruses withouth envelopes
gram-positive
viruses with lipid envelopes