Ch 11 Control Of Microbes

Question 0

Define disinfection

Answer 0

Destroys or removes most microbial life but not endospores, reducing contamination on inanimate surfaces

Question 1

Define sterilization

Answer 1

The complete destruction or removal of all microbial life including endospores

Question 2

Define antisepsis

Answer 2

Using chemicals called antiseptics to destroy or inhibit most microbial life, reducing contamination on animate surfaces

Question 3

Define decontamination

Answer 3

The mechanical removal of most microbes from animate or inanimate surfaces. Does not use chemicals. Ex: filters

Question 4

Define sanitization

Answer 4

Any cleansing technique that mechanically removes microbes as well as other debris

Question 5

What does Bacteriocidal or bactericide do

Answer 5

Chemical that destroys bacteria, does not kill endospores

Question 6

What does sporicidal or sporicide do

Answer 6

Chemical that destroys endospores

Question 7

Bacteriostatic agents _____

Answer 7

Agents that prevent growth of bacteria on tissues or on objects in the environment

Question 8

What two things have the highest resistance rating

Answer 8

Endospores and prions

Question 9

What things have a moderate resistance rating

Answer 9

Some viruses, naked ones, more resistant; hepatitis B and poliovirus

Question 10

Three specific bacteria that have moderate resistance ratings

Answer 10

Mycobacterium tuberculosis, Staphylococcus aureus, Pseudomonas

Question 11

What things have a low resistance rating

Answer 11

Most bacteria vegetative cells, fungus - yeast, enveloped viruses

Question 12

Four factors that affect the rate of microbial death

Answer 12

Length of exposure of the agent, microbial load, relative resistance, action of agent (cidal vs static)

Question 13

An example of antimicrobial effects on cell wall

Answer 13

Alcohol can dissolve the outer membrane of the cell wall of gram-negative bacteria

Question 14

What are surfactants

Answer 14

Detergents that have hydrophilic and hydrophobic regions that can physically bind to the phospholipid bilayer. Causes membrane to have open spots and creates leaks.

Question 15

Three examples of when the mode of antimicrobial action is to disrupt the genetic molecules

Answer 15

Interferes with protein synthesis, interferes with DNA replication, mutate DNA

Question 16

What is the thermal death time (TDT)

Answer 16

Shortest length of time required to kill all microbes at a specified temperature

Question 17

What is thermal death point (TDP)

Answer 17

The lowest temperature required to kill all microbes in a sample in 10 minutes

Question 18

Two examples of dry heat and what they accomplish

Answer 18

Dry oven, incineration; sterilization

Question 19

Moist heat can accomplish what

Answer 19

Sterilization and disinfection

Question 20

Two examples of steam under pressure and what it accomplishes

Answer 20

Pressure cooker, autoclave; sterilization

Question 21

Three examples of steam not under pressure

Answer 21

Pasteurization, boiling, Tyndallization

Question 22

Describe pasteurization

Answer 22

Disinfection of beverages. Technique in which heat is applied to liquids to kill potential agents of infection and spoilage, while still preserving the flavor and food value

Question 23

Tyndallization

Answer 23

Intermittent sterilization; ex: Day 1: kills vegetative cells but not spores; day 2: spores germinated over night now get killed; day 3: kills off anything remaining

Question 24

Boiling is only for _____

Answer 24

Disinfection

Question 25

What type of control does cold have

Answer 25

Only retards the metabolic activities; slows metabolism does not kill

Question 26

Desiccation

Answer 26

Loss of water due to being in a hypertonic environment. Dries it out; effective against everything except large cocci

Question 27

Osmotic pressure

Answer 27

Loss of water due to being in a hypertonic environment due to high content of salt and sugars; large cocci do better; ex: process of curing or pickling

Question 28

What is radiation

Answer 28

Energy that travels in the form of waves. Type of cold sterilization; causes mutations so severe that bacteria can’t survive it

Question 29

Irradiation

Answer 29

Bombardment of radiation

Question 30

Describe nonionizing radiation and give example

Answer 30

Does not cause the ionization of water, causes pyrimidine dimers to form. Ex: UV germicidal lamps

Question 31

What are pyrimidine dimers

Answer 31

Formed when a covalent bond is formed between 2 adjacent pyrimidines (thymine and cytosine) in a DNA strand

Question 32

Ionizing radiation and examples

Answer 32

Causes the ionization of water; “free radicals “; Ex: x-rays, gamma rays

Question 33

Filtration and examples

Answer 33

Mechanical removal. Ex: HEPA filters (high efficiency particulate air filters)

Question 34

Name six methods of physical control of microbes

Answer 34

Heat, cold, desiccation, osmotic pressure, radiation, filtration

Question 35

What is the most common method of physical control of microbes

Answer 35

Heat

Question 36

Explain halogens and give examples

Answer 36

All tend to form acids with water; bacteriocidal, sporicidal at higher concentrations; Ex: Chlorine, iodine, bromine.

Question 37

How is chlorine a chemical agent of microbial control

Answer 37

It will form an acid when combined with water: Denatures enzymes.
Cl + H2O = HCL

Question 38

Example of iodine and how it works

Answer 38

Betadine, interferes with hydrogen bonds and disulfide cross bridges in proteins

Question 39

How is alcohol an effective chemical agent of microbial control

Answer 39

Dissolves the outer membrane of Gram negative microbes

Question 40

How does hydrogen peroxide work

Answer 40

Forms free radicals which are toxic especially to any anaerobe

Question 41

How do detergents work

Answer 41

Surfactants - disrupt the bilayer