chapter 13!

Question 1

sterilization

Answer 1

the removal or destruction of ALL living microbes and endospores.
most common method is heating.

Question 2

sterilant

Answer 2

sterilizing agent

Question 3

disinfectant

Answer 3

chemical used to treat inert/non-living surfaces.

Question 3

disinfection

Answer 3

control directed at destroying harmful microbes, only vegetative (actively diving) cells, NO ENDOSPORES.

Question 4

antisepsis

Answer 4

same treatment as a disinfectant, aimed directed at destroying harmful microbes, but for LIVING tissue.

Question 5

antiseptic

Answer 5

chemical used to treat living tissue.

Question 6

degerming

Answer 6

mechanical removal most microbes on a limited area.
handwashing and alcohol swab.

Question 7

sanitization

Answer 7

lowers microbial counts, not to zero, but enough to be at safe public health levels and minimize the chances of disease transmission.
method: using high-temperature washing.

Question 8

biocide

Answer 8

kills microbes

other types: fungicide, virucide.

Question 9

bacteriostasis

Answer 9

inhibits the growth and replication of bacteria + keeps it STEADY.
once removed, growth may resume.

Question 10

sepsis

Answer 10

bacterial contamination.

Question 11

asepsis

Answer 11

the absence of significant contamination.

Question 12

aseptic

Answer 12

indications an object or area is free of pathogens.

Question 13

the rate of microbial death:

Answer 13

1. bacterial populations die at a constant rate when heated or treated with antimicrobe chemicals, which is plotted logarithmically. time it takes to kill = the number of microbes.
2. the number of microbes, environmental influence, time of exposure, and microbial characteristics influence the effectiveness of anti-microbes.

Question 14

microbial growth agents can:

Answer 14

1. cause damage to the plasma membrane (cellular contents leak)
2. cause damage to proteins (enzyme function)
3. cause damage to nucleic acids (replication and metabolic processes)

Question 15

what are the 2 physical methods of microbial control?

Answer 15

1. heat
2. radiation

Question 16

thermal death point

Answer 16

the lowest temperature at which all microbes in a fluid culture will be killed in 10 minutes.

Question 17

thermal death time

Answer 17

the minimal time required to kill all the bacteria in a liquid culture at a given temperature.

Question 18

decimal reduction time

Answer 18

the length in time at which 90% of a bacterial population will be killed at a given temperature.

Question 19

moist heat sterilization includes:

Answer 19

• boiling or free-floating steam
• autoclave (kills endospores)
• pasteurization: reduced spoilage organisms and pathogens by using a high temp for a short amount of time.
• all 3: coagulates and denatures proteins ! mechanism to damage enzymes.

Question 20

dry heat sterilization includes:

Answer 20

• direct flaming to sterlize tools like loops.
• inceneration.
• kills microbes by oxidation effects.

Question 21

radiation includes:

Answer 21

1. ionizing radiation: x-rays, gamma rays, electron beams. ionizes water to create reactive hydroxyl radicals to damage DNA and cause lethal mutations. shorter wavelength.
2. non-ionizing radiation: damages DNA by creating thymine dimers. (ex. sun radiation leads to cancer). longer wavelength.
3. microwaves.

Question 22

chemical methods of microbial control:

Answer 22

• are used on living tissue (anti-septic) and on inanimate objects (disinfectants).
• most chemical agents only reduce microbe populations to safe levels + remove vegetative (active) cells, not achieve sterility.

Question 23

principles of effective disinfection:

Answer 23

1. concentration of effective disinfection
2. organic matter
3. pH
4. time

Question 24

the disk diffusion method:

Answer 24

• evaluates the effectiveness of a chemical agent
• filter paper discs are soaked in a chemical agent and placed on a culture.
• zone of inhibition

Question 25

agents that disrupt the plasma membrane:

Answer 25

1. phenol: carbolic acid.
2. phenolics: cresol and o-phenylphenol. disinfectant.
3. biphenols: hexachlorophene and triclosan. disinfectant.
4. biguanides: chlorhexidine. antiseptic
5. essential oils: peppermint, pine, and orange oil.
6. surface active agents: soaps. degerming.

Question 26

agents that impair protein synthesis AND alter the plasma membrane:

Answer 26

1. halogens: iodine and chlorine. disinfectant.
2. alcohol: ethanol and isopropanol. antiseptic and disinfectant.

Question 27

agents that cause protein denaturation ONLY:

Answer 27

1. heavy metals: silver nitrate and silver sulfadiazine.
2. aldehydes: formaldehyde and glutaraldehyde. sterilizing agent. mycobacteria.