Ch.7 microbial control

Question 1

refers to bacterial contamination

Answer 1

Sepsis

Question 2

is the absence of significant contamination

Aseptic surgery techniques prevent the microbial contamination of wounds

Answer 2

Asepsis

Question 3

removing and destroying all microbial life

Keyword: your not just removing but your destorying

Answer 3

Sterilization

Question 4

killing Clostridium botulinum endospores from canned goods

Answer 4

Commercial sterilization

Question 5

destroying harmful microorganisms

keword: just destroying

Answer 5

Disinfection

Question 6

destroying harmful microorganisms from living tissue

Keyword :tissue

Answer 6

Antisepsis

Question 7

the mechanical removal of microbes from a limited area

Keyword: mechanical and limited area

Answer 7

Degerming

Question 8

lowering microbial counts on eating utensils to safe levels

keyword: utensils

Answer 8

Sanitization

Question 9

treatments that kill microbes

keyword: treatments

Answer 9

Biocide (germicide):

Question 10

inhibiting, not killing, microbes

Answer 10

Bacteriostasis

Question 11

Usual definition of sterilization is the removal or destruction of all forms of microbial life; how could there be practical exceptions to this simple definitions?

Answer 11

Prions have a high resistance to all forms of sterilization; sterilization implies to the absence of prions.

Question 12

How is it possible that a solution containing a million bacteria would take longer to sterilize than one containing a half-million bacteria?

Answer 12

The more microbes to begin with, the longer it takes to eliminate the entire population.

Question 13

Effectiveness of treatment depends on:

Answer 13

Number of microbes
Environment (organic matter, temperature, biofilms)
Time of exposure
Microbial characteristics

Question 14

Actions of Microbial Control Agents include

Answer 14

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

Question 15

Would a chemical microbial control agent that affects plasma membranes affect humans?

Answer 15

yes human cells have plasma membranes
it is best to use microbial agents that attack certain components of the microorganism that are not present in the host cell
For example, penicillin is an antibiotic that targets the cell well. Since the cell wall is not present in human cells, penicillin causes no damage to the host cell.

Question 16

what does heat do to the organism?

Answer 16

denatures the enzyme

Question 17

Thermal death point?

Answer 17

the temperature it takes for the organism to die at 10 min

Question 18

thermal death time

Answer 18

the time it takes for the organism to die at a particular temperature

Question 19

Decimal reduction time (DRT)

Answer 19

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

Question 20

moist heating includes ?

Answer 20

boiling, autoclave, and pasteurization

Question 21

what does moist heat do?

Answer 21

coagulates/denatures proteins

Question 22

what is the autoclave?

and what does it do?

Answer 22

steam under pressure
Kills all organisms and endospores
Steam must contact the item’s surface

Question 23

___require longer sterilization times

____are used to indicate sterility

Answer 23

large containers

test strips

Question 24

Pasteurization?

what are the two equivalents of pasteurization?

Answer 24

reduces spoilage organisms and pathogens by heating materials for a short time

High-temperature short-time (HTST): 72°C for 15 sec
Ultra-high-temperature (UHT): 140°C for 4 sec

Question 25

relatively heat-resistant) organisms survive

Answer 25

Thermoduric

Question 26

how does dry heat sterilization kill?

Answer 26

Flaming Incineration Hot-air sterilization

Question 27

what is filtration?

Answer 27

Passage of substance through a screenlike material | Used for heat-sensitive materials

Question 28

High-efficiency particulate air (HEPA) filters

Answer 28

remove microbes > 0.3 μm in diameter

Question 29

Membrane filters

Answer 29

remove microbes > 0.22 μm | Pore sizes of as small as 0.01 μm are available, which can filter out viruses and large proteins

Question 30

what are the Physical Methods of Microbial Control?

Answer 30

low temp high pressure desiccation osmotic pressure

Question 31

what does low temp do? what does high pressure do? what does desiccation do? what does osmotic pressure do?

Answer 31

has a bactderiostatic effect denatures proteins absence of water prevents metabolism high conc of salts and sugers creat hypertonic solution causing plasmolysis

Question 32

Ionizing radiation what does it do?

Answer 32

Ionizes water to create reactive hydroxyl radicals | Damages DNA by causing lethal mutations

Question 33

Nonionizing radiation (ultraviolet, 260 nm)

Answer 33

Damages DNA by creating thymine dimers

Question 34

How is microbial growth in canned foods prevented?

Answer 34

Drying is often used to preserve foods (e.g. fruits, grains, etc.). Methods involve removal of water from commercial sterilization: product by heat, evaporation, freeze-drying, and addition of salt or sugar.

Question 35

Why would a can of pork take longer to sterilize at a given temperature than a can of soup that also contained pieces of pork?

Answer 35

Solid foods heat unevenly because of the uneven distribution of moisture.

Question 36

What is the connection between the killing effect of radiation and hydroxyl radical forms of oxygen?

Answer 36

These radicals are produced from ionizing radiation that take electrons from other molecules.

Question 37

Principles of Effective Disinfection?

Answer 37

Concentration of disinfectant Organic matter pH Time

Question 38

Use-Dilution Tests?

Answer 38

Metal cylinders are dipped in test bacteria and dried Cylinders are placed in disinfectant for 10 min at 20°C Cylinders are transferred to culture media to determine whether the bacteria survived treatment tests the lowest amount of chemical needed to efficiently kill a microbe

Question 39

The Disk-Diffusion Method

Answer 39

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

Question 40

If you wanted to disinfect a surface contaminated by vomit and a surface contaminated by a sneeze, why would your choice of disinfectant make a difference?

Answer 40

no single chemical is good for all applications. It would depend on what the situation dictates

Question 41

Which is more likely to be used in a medical clinic laboratory, a use-dilution test, or a disk-diffusion test?

Answer 41

Disk-diffusion test. Because this is what is used to measure the effectiveness of specific antibiotics on certain microbes. -A use-dilution test would be more appropriate in industrial uses because it measures what is the lowest amount of chemical needed in a solution to effectively kill microbes