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Exam 3, Chapter 7

front 1

THE TERMINOLOGY OF MICROBIAL CONTROL

Aseptic Surgery

back 1

Techniques used in surgery to prevent microbial contamination from the instruments, operating personnel, and the patient.

front 2

THE TERMINOLOGY OF MICROBIAL CONTROL

Sterilization

back 2

The destruction or removal of all microbial life, including endospores.

front 3

THE TERMINOLOGY OF MICROBIAL CONTROL

How do you sterilize liquids or gases?

back 3

By using filtration.

front 4

THE TERMINOLOGY OF MICROBIAL CONTROL

Sterilant

back 4

Is a sterilizing agent.

front 5

THE TERMINOLOGY OF MICROBIAL CONTROL

Commercial Sterilization

back 5

The process of treating canned goods aimed at destroying the endospores of Clostridium botulinum (a kind of food poisoning).

front 6

THE TERMINOLOGY OF MICROBIAL CONTROL

Why is commercial sterilization important?

back 6

Clostridium botulinum produces a deadly toxin. More-resistant endospores of thermophilic (heat-loving) bacteria are capable of causing food spoilage but not human disease, and they will not germinate and grow at normal food storage temperatures.

front 7

THE TERMINOLOGY OF MICROBIAL CONTROL

Disinfection

back 7

Any treatment used on inanimate objects to kill or inhibit the growth of microorganisms; removing pathogens.

front 8

THE TERMINOLOGY OF MICROBIAL CONTROL

Antisepsis

back 8

A chemical method for disinfection of the skin and mucous membranes; removing pathogens from living tissues.

front 9

THE TERMINOLOGY OF MICROBIAL CONTROL

Antiseptic

back 9

Is the chemical used to perform the antisepsis technique.

front 10

THE TERMINOLOGY OF MICROBIAL CONTROL

Sepsis

back 10

The presence of a toxin or pathogenic organism in blood and tissue; refers to microbial contamination.

front 11

THE TERMINOLOGY OF MICROBIAL CONTROL

Asepsis

back 11

The absence of contamination by unwanted organisms.

front 12

THE TERMINOLOGY OF MICROBIAL CONTROL

Degerming

back 12

The mechanical removal of microorganisms in an area or injection site, rather than killing them; also called degermation.

front 13

THE TERMINOLOGY OF MICROBIAL CONTROL

Sanitization

back 13

The removal of microorganisms from eating utensils and food preparation areas.

front 14

Biocide, or Germicide

back 14

A substance capable of killing microorganisms (except endospores).

front 15

THE TERMINOLOGY OF MICROBIAL CONTROL

Suffix -cide

back 15

Names of treatments that cause the outright death of microbes; meaning kill.

front 16

Bacteriostasis

back 16

A treatment capable of inhibiting bacterial growth.

front 17

EFFECTIVENESS OF TREATMENT

Depends on:

back 17

1. The number of microbes.

2. Environment (organic matter, temperature,
biofilms).

3. The time of exposure.

4. Microbial characteristics.

front 18

ACTION OF MICROBIAL CONTROL AGENTS

back 18

1. Alterations of membrane permeability.

2. Damage to proteins.

3. Damage to nucleic acids.

front 19

HEAT

Thermal death point (TDP)

back 19

The temperature required to kill all the bacteria in a liquid culture in 10 minutes.

front 20

HEAT

Thermal death time (TDT)

back 20

The length of time required to kill all bacteria in a liquid culture at a given temperature.

front 21

HEAT

Decimal reduction time (DRT)

back 21

The time (in minutes) required to kill 90% of a bacterial population at a given temperature; also called D value.

front 22

MOIST HEAT STERILIZATION

back 22

Moist heat denatures proteins.

front 23

MOIST HEAT STERILIZATION

Autoclave

back 23

Equipment for sterilization by steam under pressure; usually operated at 15 psi and 121°C to kill all organisms (except prions)and their endospores in about 15 minutes; guaranteed complete sterilization.

front 24

Pasteurization

back 24

The process of mild heating to kill particular spoilage microorganism or pathogens; normal pasteurization is 63°C for 30 minutes; does not achieve complete sterilization only reduces microbes.

front 25

PASTEURIZATION

back 25

1. Reduces spoilage organisms and pathogens.

2. EQUIVALENT TREATMENTS:
a) 63°C for 30 min
b) High-temperature short-time
c) Ultra-high-temperature
d) Thermoduric organisms survive

front 26

PASTEURIZATION

High-temperature short-time (HTST) pasteurization

back 26

Pasteurization at 72°C for 15 seconds.

front 27

PASTEURIZATION

Ultra-high-temperature (UHT)treatments

back 27

A method of treating food with high temperatures (140-150°C for 4 seconds) for very short times to make food sterile so that it can be stored at room temperature.

front 28

What are the differences between HTST and UHT?

back 28

1. HTST is pasteurization and has to be
refrigerated for a certain amount of time
(usually 2 weeks) before it spoils.

2. UHT is sterilized and can be stored for several
months without refrigeration; an example is
the small coffee creamers found in restaurants.

front 29

Thermoduric bacteria

back 29

Heat resistant; survive pasteurization; unlikely to cause disease or cause refrigerated milk to spoil.

front 30

DRY HEAT STERILIZATION

Kills by:

back 30

1. Dry heat

2. Flaming

3. Incineration

4. Hot-air sterilization

front 31

DRY HEAT STERILIZATION

Dry heat

back 31

Kills by oxidation effects.

front 32

DRY HEAT STERILIZATION

Flaming

back 32

The process of sterilizing an inoculating loop by holding it in an open flame.

front 33

DRY HEAT STERILIZATION

Incineration

back 33

Burning to ashes.

front 34

DRY HEAT STERILIZATION

Hot-air sterilization

back 34

Sterilization by the use of an oven at 170°C for approximately 2 hours.

front 35

DRY HEAT STERILIZATION

Equivalent treatments

back 35

Different methods that have the same effect on controlling microbial growth.

front 36

FILTRATION

back 36

The passage of a liquid or gas through a screenlike material; a 0.45µm filter removes most bacteria; heat labile (sensitive)substances should be sterilized by filtration and not heat.

front 37

FILTRATION

High-efficiency particulate air (HEPA) filters

back 37

A screenlike material that removes particles greater than 0.3µm from air.

front 38

FILTRATION

Membrane filters

back 38

A screen-like material with pores small enough to remove microbes greater than 0.22µm from air; a 0.45µm filter retains most bacteria; used for liquids.

front 39

FILTRATION

Filterable viruses

back 39

Unseen pathogens that passed through the filters (causing such disease as rabies) made of unglazed porcelain in the early days of microbiology.

front 40

PHYSICAL METHODS OF MICROBIAL CONTROL

Kills by:

back 40

1. Low temperature

2. High pressure

3. Desiccation

4. Osmotic pressure

front 41

PHYSICAL METHODS OF MICROBIAL CONTROL

Low temperature

back 41

1. Creates a bacteriostatic effect at temperatures of ordinary refrigerators (0-7°C) because it reduces the metabolic rate of most microbes so that they cannot reproduce or synthesize toxins; rapidly attained subfreezing temperatures tend to render microbes dormant but do not necessarily kill them.

2. INHIBITS MICROBIAL GROWTH:
a) Refrigeration
b) Deep-freezing
c) Lyophilization

front 42

PHYSICAL METHODS OF MICROBIAL CONTROL

Lyophilization

back 42

In the absence of water (desiccation) microorganisms cannot grow or reproduce but can remain viable for years and then resume their growth and division once water is made available to them; also called freeze-drying, which is a laboratory process for preserving microbes.

front 43

PHYSICAL METHODS OF MICROBIAL CONTROL

High pressure

back 43

Denatures proteins

front 44

PHYSICAL METHODS OF MICROBIAL CONTROL

Desiccation

back 44

The removal of water; drying; prevents metabolism.

front 45

PHYSICAL METHODS OF MICROBIAL CONTROL

Osmotic pressure

back 45

High concentrations of salt and sugars causes PLASMOLYSIS which is the loss of water from a cell in a hypertonic environment; can't metabolize but inhibits their growth

front 46

RADIATION

Types:

back 46

1. Ionizing radiation

2. Nonionizing radiation

3. Microwaves

front 47

RADIATION

Ionizing radiation

back 47

1.Gamma rays, X rays, or High-energy electron
beams, has a wavelength shorter than that of
nonionizing radiation less than about 1nm.

2. Ionizes water to release OH.

3. Damages DNA.

front 48

RADIATION

Non-ionizing radiation

back 48

1. Short-wavelength radiation that does not cause
ionization; radiation is not very penetrating;
ultraviolet (UV) radiation (260nm) is an
example.

2. Damages DNA.

front 49

RADIATION

Microwaves

back 49

1. Electromagnetic radiation.

2. Kill by radiation; not especially antimicrobial.

front 50

PRINCIPLES OF EFFECTIVE DISINFECTION

back 50

1. Concentration

2. Organic matter

3. pH

4. Time

front 51

USE-DILUTION TEST

back 51

1. A method of determining the effectiveness of a
disinfectant using serial dilutions.

2. Metal rings dipped in test bacteria are dried.

3. Dried cultures are placed in disinfectant for 10 min at 20°C.

4. Rings are transferred to culture media to
determine whether bacteria survived treatment.

front 52

DISK-DIFFUSION METHOD

back 52

An agar-diffusion test to determine microbial susceptibility to chemotherapeutic agents; also called Kirby-Bauer test.

front 53

Phenol

back 53

Also called carbolic acid; first used by Lister to control surgical infections in the operating room.

front 54

Phenolics

back 54

A derivative of phenol used as a disinfectant.

front 55

PHENOL & PHENOLICS

back 55

Disrupt plasma membranes

front 56

Cresol

back 56

Phenolic derived from coal tar; are very good surface disinfectants.

front 57

Why are phenolics useful as disinfectants?

back 57

1. They remain active in the presence of organic
compounds.
2. They are stable.
3. They persist for long periods after
application.

front 58

Bisphenols

back 58

1. A derivative of phenol that contains two phenol
groups connected by a bridge (bis indicates
two).

2. HEXACHOLORPHENE, TRICLOSAN:
disrupt plasma membrane

front 59

Hexachlorophene

back 59

A type of bisphenol used to control infections in nurseries; excessive use on infants can lead to nerve damage.

front 60

Triclosan

back 60

A bisphenol used in antibacterial soaps, at least one toothpaste, and kitchen cutting boards and plastics; it inhibits an enzyme needed for the biosynthesis of fatty acids (lipids), which mainly affects the plasma membrane; effective againt gram positive bacteria and also works well against gram-negative bacteria.

front 61

Biguanides

back 61

CHLORHEXIDINE:
disrupt Plasma membrane

front 62

Chlorhexidine

back 62

A Biguanide used for microbial control on skin and mucous membranes.

front 63

Fungicide

back 63

A substance capable of killing fungi.

front 64

Virucide

back 64

A substance capable of inactivating viruses.

front 65

Suffix -stat or -stasis

back 65

Names of treatments that inhibit the growth and multiplication of bacteria; meaning to stop or to steady.

front 66

Several factors influence the effectiveness of antimicrobial treatments:

back 66

1. The number of microbes
2. Environmental influences:
a. Organic matter
b. Microbes in surface biofilms
c. Suspended medium
3. Time of exposure
4. Microbial characteristics

front 67

The number of microbes

back 67

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

front 68

Environmental influences

Organic matter

back 68

Inhibits the action of chemical antimicrobials.

front 69

Environmental influences

Microbes in surface biofilms

back 69

Are difficult for biocides to reach effectively. Because their activity is due to temperature-dependent chemical reactions, disinfectants work somewhat better under warm conditions.

front 70

Environmental influences

Suspended in medium

back 70

Fats and proteins are especially protective, and a medium rich in these substances protect microbes, which will then have a higher survival rate.

front 71

Time of exposure

back 71

Chemical antimicrobials often require extended exposure to affect more-resistant microbes or endospores.

front 72

Microbial characteristics

back 72

Affect the choice of chemical and physical control methods.

front 73

Cell membrane permeability

back 73

This membrane actively regulates the passage of nutrients into the cell and the elimination of waste from the cell.

front 74

Functional properties of proteins

back 74

Are the result of their three-dimensional shape.

front 75

What physical methods are used as heat techniques?

back 75

1. Moist heat:
a) Boiling or flowing stream
b) Autoclaving

2. Pasteurization

3. Dry heat:
a) Direct flaming
b) Incineration
c) Hot-air sterilization

front 76

Retorts

back 76

A device for commercially sterilizing canned food by using steam under pressure; operates on the same principle as an autoclave but is much larger.

front 77

Boiling or flowing stream

back 77

Kills vegetative forms of bacterial pathogens, almost all viruses, and fungi and their spores within about 10 minutes; 100°C is considered boiling; does not kill endospores so it is not considered a complete sterilization.

front 78

What does the phosphate test, test for?

**phosphatase is an enzyme naturally present in milk**

back 78

To determine whether products have been pasteurized; phosphatase products will be inactived if the product has been pasteurized.

front 79

What types of bacteria and what types of virus can resist boiling? And for how long?

back 79

1. Some hepatitis viruses, can resist up to 30
minutes of boiling.

2. Some bacterial endospores, can resist boiling
for more than 20 hours.

front 80

Sterilization in an autoclave is most effective when?

back 80

1. The organisms are contacted by the steam
directly.

2. Or contained in a small volume of aqueous
(primarily water) liquid.

front 81

What physical methods are used as cold techniques?

back 81

1. Refrigeration

2. Deep-freezing

3. Lyophilization

front 82

Halogens

back 82

One of the following elements: fluorine, chlorine, bromine, iodine, or astatine.

front 83

HALOGENS-IODINE

Tincture

back 83

A solution in aqueous alcohol and is an iodophor.

front 84

HALOGENS-IODINE

Iodophors

back 84

A combination of iodine and an organic molecule, from which the iodine is released slowly; have the antimicrobial activity of iodine, but they do not stain and are less irritating.

front 85

HALOGENS

Chlorine

back 85

1. BLEACH:
Hypochlorous acid (HOCI)

2. CHLORAMINE:
Chlorine + ammonia

3. Oxidizing agents

front 86

Alcohols

back 86

1. An organic molecule with the functional group-
OH.

2. ETHANOL, ISOPROPANOL:
a) denature proteins, dissolve lipids
b) require water

front 87

Pseudomonas aeruginosa

back 87

A gram-negative bacteria that is very resistant to triclosan, and many other antibiotics and disinfectants.

front 88

HEAVY METALS

Ag, Hg, Cu

back 88

1. Silver Nitrate may be used to prevent
gonorrheal opthalmia neonatorum.

2. Silver Sulfadiazine used as a topical cream on
burns.

3. Copper Sulfate is an algicide.

front 89

HEAVY METALS

Oligodynamic action

back 89

The ability of small amounts of a heavy metal compound to exert antimicrobial activity; oligo means few; denatures proteins.

front 90

SURFACE-ACTIVE AGENTS, OR SURFACTANTS

Surface-active agents

back 90

Any compound that decreases the tension between molecules lying on the surface of a liquid; also called surfactant.

front 91

SURFACE-ACTIVE AGENTS, OR SURFACTANTS

Soap

back 91

Degerming

front 92

SURFACE-ACTIVE AGENTS, OR SURFACTANTS

Acid-anionic detergents

back 92

Sanitizing

front 93

SURFACE-ACTIVE AGENTS, OR SURFACTANTS

Quaternary ammonium compounds (cationic detergents)

back 93

Bactericidal, denature proteins, disrupt plasma membrane.

front 94

Quaternary ammonium compounds (quats)

back 94

A cationic detergent with four organic groups attached to a central nitrogen atom; used as a disinfectant; are less effective against gram-negative bacteria and more effective against gram positive bacteria.

front 95

Sulfar dioxide ( SO‚₂)

back 95

Disinfectant used in wine-making.

front 96

Sorbic acid, potassium sorbate, sodium benzoate

back 96

Prevent molds from growing on acidic foods, such as cheese and soft drinks.

front 97

Calcium propionate

back 97

An effective fungistat used in bread, prevents the growth of surface molds and the Bacillus bacterium that causes ropy bread.

front 98

Sodium nitrate and Sodium nitrite

back 98

Are added to many meat products, such as ham, bacon, hot dogs, and sausage.

front 99

How do the bacteria in meats use nitrate?

back 99

As a substitute for oxygen under anaerobic conditions.

front 100

What are the 2 main functions of nitrite?

back 100

1) To preserve the red color of the meat by reacting with blood components in the meat.

2) To prevent the germination and growth of any botulism endospores that might be present.

front 101

Nitrosamines

back 101

A carcinogen formed by the combination of nitrite and amino acids.

front 102

ALDEHYDES

back 102

1. An organic molecule with the functional group-
CHO.

2. Inactivates proteins by cross-linking with
functional groups (-NH₂, -OH, -COOH, -SH)

3. USE: MEDICAL EQUIPMENT
a) Glutaraldehyde, formaldehyde, and ortho-
phthalaldehyde.

front 103

GASEOUS STERILANTS

back 103

1. Denature proteins

2. USE: HEAT-SENSITIVE MATERIAL
a) Ethylene oxide

front 104

PLASMA

back 104

1. The liquid portion of blood in which the formed
elements are suspended.

2. Exited gases used for sterilization.

3. Free radicals destroy microbes.

4. USE: TUBULAR INSTRUMENTS

front 105

SUPERCRITICAL FLUIDS

back 105

1. CO₂with gaseous and liquid properties.

2. USE: MEDICAL IMPLANTS

front 106

PEROXYGENS

back 106

1. A class of oxidizing-type sterilizing
disinfectants.

2. Oxidizing agents.

3. USE: CONTAMINATED SURFACES
a) O3, H₂O₂, peracetic acid

front 107

CHEMICAL FOOD PRESERVATIVES

ORGANIC ACID

back 107

1. Inhibits metabolism.

2. Sorbic acid, benzoic acid, and calcium
propionate.

3. Control molds and bacteria in foods and
cosmetics.

front 108

CHEMICAL FOOD PRESERVATIVES

Nitrite

back 108

Prevents endospore germination.

front 109

CHEMICAL FOOD PRESERVATIVES

Antibiotics

back 109

Nisin and Natamycin prevent spoilage of cheese.

front 110

Nisin

back 110

Is often added to cheese to prevent the growth of certain endospore-forming spoilage bacteria.

front 111

Natamycin (primaricin)

back 111

Is an antifungal antibiotic approved for use in foods, mostly cheese.

front 112

MICROBIAL CHARACTERISTICS

back 112

IN ORDER FROM MOST RESISTANT TO LEAST RESISTANT:

Prions

Endospores of bacteria

Mycobacteria

Cysts of protozoa

Vegetative protozoa

Gram-negative bacteria

Fungi, including most fungal spores

Viruses without envelopes

Gram-positive bacteria

Viruses with lipid envelopes

front 113

Sterilization is the:

A) same as sanitization.
B) destruction of all forms of microbial life
except endospores.
C) effective removal of all microbes on a
surface.
D) destruction of all life forms.
E) control of all microbial growth.

back 113

Destruction of all life forms.

front 114

An antiseptic is used when one needs to remove microbes from:

A) food preparation areas.
B) foods, prior to canning.
C) toilet surfaces.
D) restaurant glassware.
E) skin, prior to injection.

back 114

Skin, prior to injection.

front 115

Foods to be canned need not be sterile. However, all ______ of Clostridium botulinum must be killed.

A) LPS
B) capsules
C) flagellar proteins
D) cells
E) endospores

back 115

Endospores

front 116

Some antimicrobial treatments kill microbes; some inhibit growth. Which term refers to an agent that inhibits bacterial growth?

A) Germicidal.
B) Bacteriostatic.
C) Fungicidal.
D) Homeostatic.
E) Bacteriocidal.

back 116

Bacteriostatic.

front 117

Which of the following is not a major target for action of antimicrobials?

A) Flagella.
B) Enzymes
C) Nucleic acids.
D) Cell membranes.
E) Proteins.

back 117

Flagella.

front 118

Decimal reduction time is the time in minutes in which _______ of the population at a given temperature will be killed.

A) 75%
B) 100%
C) 10%
D) 80%
E) 90%

back 118

90%

front 119

Which is not a characteristic of the autoclave?

A) The ability to sterilize solutions with
endospores.
B) The use of high temperatures.
C) The use of moist heat.
D) The use of high pressures.
E) The requirement for long (hours) exposure
times.

back 119

The requirement for long (hours) exposure times.

front 120

Milk that you have never opened spoils in the refrigerator. A sample reveals the presence of microorganisms. The most likely explanation is:

A) the pasteurization process was ineffective.
B) the microbes are pathogens.
C) the microbes that survived pasteurization were
able to grow at 4 °C.
D) there was a leak in the milk carton that
allowed microbes to enter.
E) pasteurization resistant mutants developed
after pasteurization.

back 120

the microbes that survived pasteurization were able to grow at 4 °C.

front 121

Pasteurization was first used by Pasteur to control spoilage of:

A) canned foods.
B) cheese.
C) wine.
D) milk.
E) yogurt.

back 121

Wine.

front 122

Choose the best method for the sterilization of an enzyme solution.

A) Filtration.
B) Freezing.
C) Autoclave
D) Pasteurization.
E) Dry heat.

back 122

Filtration.

front 123

The bactericidal effect of UV light is attributed to damage to:

A) plasma membranes.
B) proteins.
C) nuclei.
D) DNA.
E) ribosomes.

back 123

DNA.

front 124

Packages of milk and coffee creamers may be stored without refrigeration if they have been sterilized by:

A) autoclaving.
B) high-temperature short-time (HTST)
pasteurization.
C) boiling.
D) ultra-high-temperature (UHT) treatment.
E) treatment with phenol.

back 124

Ultra-high-temperature (UHT) treatment.

front 125

All of the following methods are used for food preservation except:

A) Direct flaming.
B) Dessication.
C) Osmotic pressure.
D) Commercial canning.
E) Deep freezing.

back 125

Direct flaming.

front 126

Some microbes are very resistant to antimicrobial chemicals. Which of the following would be the easiest to kill?

A) E. coli.
B) Cysts of protozoa
C) Pseudomonas aeruginosa
D) Mycobacterium tuberculosis
E) Clostridium endospores

back 126

E. coli.

front 127

Which type of radiation is least effective in killing microbes?

A) Microwaves
B) Gamma rays
C) Ultraviolet rays
D) High-energy electron beams
E) X rays

back 127

Microwaves

front 128

The first disinfectant used by Lister was ________.

A) iodine.
B) chlorine.
C) Listerine.
D) Betadine.
E) phenol.

back 128

Phenol.

front 129

Alcohol is most effective when used as a solution.

A) 70%
B) 60%
C) 25%
D) 95%
E) 100%

back 129

70%

front 130

All of the following are examples of microbial control using heavy metals except:

A) antiseptic solution containing mercurochrome.
B) benzoyl peroxide used for acne treatment.
C) algae control in swimming pools using copper
sulfate.
D) burn treatment using silver-sulfadiazine
ointment.
E) mouthwash solution containing zinc chloride.

back 130

Benzoyl peroxide used for acne treatment.

front 131

______ is a compound found in antimicrobial soaps that targets gram-positive bacteria.

A) Formaldehyde
B) Hydrogen peroxide
C) Sodium nitrate
D) Triclosan
E) Mercuric chloride

back 131

Triclosan.

front 132

The following may be listed on the ingredients of your favorite snack food. Which of the following is not antimicrobial?

A) Xanthan.
B) Calcium propionate.
C) Potassium sorbate.
D) Sorbic acid.
E) Sodium benzoate.

back 132

Xanthan.

front 133

Microbes vary with respect to sensitivity to an antimicrobial agent.

back 133

True.

front 134

The presence of organic matter, such as blood or saliva, speeds the action of antimicrobial chemicals.

back 134

False.

front 135

All bacteria die at once when they are exposed to heat or chemical treatment.

back 135

True.

front 136

Times required for sterilization in an autoclave are shorter than those required in a dry oven because moist heat penetrates biological specimens more effectively than does dry heat.

back 136

True.

front 137

Ethylene oxide gas is used to sterilize medical equipment that might be damaged by exposure to the heat of autoclaving.

back 137

True.

front 138

UV radiation and X ray radiation are similar in that they damage DNA and have a high penetrating power.

back 138

False.

front 139

Iodine is one of the least effective antimicrobial chemicals, effective only against certain very sensitive strains of bacteria.

back 139

False.

front 140

Soap is ineffective in killing bacteria. Therefore, hand washing is a rather ineffective measure in preventing disease transmission.

back 140

False.

front 141

Most disinfectants can be used as antiseptics.

back 141

False.

front 142

70% ethyl alcohol is a more effective bactericide than 100% alcohol.

back 142

True.

front 143

According to the figure, at what rate are the cells dying?

A) 1% each minute
B) 10% each minute
C) 50% each minute
D) 90% each minute
E) 99% each minute

back 143

90% each minute

front 144

In the figure shown, what is the method of sterilization used?

A) Autoclave
B) High pressure
C) Osmotic pressure
D) Radiation
E) Filtration

back 144

Filtration

front 145

In the photo shown, it can be concluded that the quaternary ammonium compound (Quat) was most effective against:

A) It is impossible to determine from the photo
B) Staphylococcus aureus
C) They are all equally affected by the quat
D) Escherichia coli
E) Pseudomonas aeruginosa

back 145

Staphylococcus aureus

front 146

All of the following conclusions are correct regarding the photos of the disk-diffusion assay EXCEPT:

A) Gram-negative bacteria are the most sensitive
to the chemicals.
B) Only one of the four chemicals affected
pseudomonas.
C) Gram-positive bacteria are the most sensitive
to the chemicals.
D) Hexachlorophene was effective against gram-
positive bacteria only.
E) Chlorine was effective against all the test
bacteria.

back 146

Gram-negative bacteria are the most sensitive to the chemicals.

front 147

All of the following conclusions are correct regarding the graph shown EXCEPT:

A) The tincture of iodine was the most effective
chemical agent.
B) Soap and water were shown to be the least
effective chemical agent.
C) By 2 minutes, 70% ethanol and 30% water had
killed 90% of the bacteria.
D) Aqueous Zephiran is more effective than the
tincture of Zephiran.

back 147

Aqueous Zephiran is more effective than the tincture of Zephiran.

front 148

The clear zones around the coins on the plate in the photo are due which phenomenon?

A) The triclosan in the coins.
B) The oligodynamic action of the metals in the
coins.
C) The halogens present in the coins.
D) The surfactants in the coins.
E) The quaternary ammonium compounds in the coins.

back 148

The oligodynamic action of the metals in the coins.

front 149

Which chemical shown is a common ingredient in antibacterial soaps and at least one toothpaste?

A) Benzalkonium chloriede (Zephiran)
B) Triclosan
C) Hexachlorophene
D) Phenol

back 149

Triclosan

front 150

You discover a compound that you suspect reduces spoilage in fruit. You treat apples with your compound and inoculate them with Botrytis, a common spoilage fungus. After seven days the dry weight of fungi on the treated apples is 5 mg and 10 mg on the untreated apples. You conclude from these results that:

A) the compound is toxic to humans.
B) the compound is fungistatic.
C) apple spoilage is caused by fungi.
D) the compound kills fungi.

back 150

The compound is fungistatic.

front 151

You contaminate kitchen counters with Salmonella enterica in chicken blood and expose it to a variety of treatments to study the survival of the bacteria on kitchen surfaces. The following DRT values were obtained: 2.0 min. at 52° C; 3.7 min. at pH 2.6; 13.3 min. with 10mM hydrogen peroxide; and >35 days without treatment. Which treatment is most effective against S. enterica?

A) acid
B) heat
C) a, b, and c are equivalent treatments
D) hydrogen peroxide

back 151

Heat.

front 152

The best definition of sterilization is the:

A) removal of all microorganisms.
B) elimination of bacteria.
C) removal of unwanted microorganisms.
D) removal of Clostridium botulinum endospores.

back 152

Removal of all microorganisms.

front 153

What is the difference between a disinfectant and an antiseptic?

A) Disinfectants kill some microorganisms;
antiseptics kill all microorganisms.
B) Disinfectants kill microorganisms; antiseptics
inhibit microbial growth.
C) Disinfectants are used on environmental
surfaces; antiseptics are used on living
tissue.
D) Disinfectants remove all microorganisms;
antiseptics remove some microorganisms.

back 153

Disinfectants are used on environmental surfaces; antiseptics are used on living tissue.

front 154

Which of the following treatments achieves sterilization?

A) pasteurization
B) boiling
C) autoclaving
D) commercial sterilization

back 154

Autoclaving.

front 155

Which one of the following is not an antiseptic?

A) iodine
B) alcohol
C) bispenol
D) soap

back 155

Soap.

front 156

Which one of the following kills cells by damaging DNA?

A) deep-freezing
B) ultraviolet light
C) alcohol
D) pasteurization

back 156

Ultraviolet light.

front 157

Which one of the following does not belong with the others?

A) bisphenol
B) iodine
C) chlorine
D) phenolic

back 157

Chlorine.

front 158

Which one of the following is not an antiseptic?

A) mercurochrome
B) iodine
C) hydrogen peroxide
D) alcohol

back 158

Hydrogen peroxide.

front 159

Which one of the following methods is bactericidal?

A) deep-freezing
B) filtration
C) lyophilization
D) none of these are bactericidal

back 159

None of these are bactericidal.

front 160

Which one of the following is effective against bacterial endospores?

A) biguanide
B) hexachlorophene
C) chlorine bleach
D) mercury

back 160

Chlorine bleach.

front 161

Which one of the following concentrations of ethyl alcohol is the most effective disinfectant?

A) 50%
B) 25%
C) 75%
D) 100%

back 161

75%

front 162

Four compounds are tested for their disinfectant activity. Compound A kills pseudomonads, mycobacteria, endospores, lipophilic viruses, and hydrophilic viruses. Compound B kills pseudomonads, mycobacteria, and lipophilic viruses. Compound C kills pseudomonads and lipophilic viruses. Compound D does not kill any of the test organisms. Which compound is most likely a soap?

A) Compound C
B) Compound B
C) Compound A
D) Compound D

back 162

Compound D.

front 163

Which of the following is not an oxidizing agent?

A) chlorine
B) hydrogen peroxide
C) triclosan
D) ozone

back 163

Triclosan.

front 164

Which one of the following is most useful for disinfecting medical instruments?

A) iodine
B) mercurochrome
C) alcohols
D) glutaraldehyde

back 164

Glutaraldehyde.

front 165

Which one of the following is generally the easiest to kill?

A) lipophilic viruses
B) hydrophilic viruses
C) Pseudomonas
D) endospores

back 165

Lipophilic viruses.

front 166

The use-dilution values for three disinfectants tested under the same conditions are: Disinfectant X- 1:10; Disinfectant Y-1:100; Disinfectant Z- 1:1,000. If the disinfectants are non-toxic and designed for the same purpose, which would you select?

A) They are equivalent treatments; it doesn't
matter.
B) Y
C) X
D) Z

back 166

Z.

front 167

The disk-diffusion test is used to test disinfectants against Staphylococcus aureus. For Disinfectant A, a 1:10 dilution gives a 25 mm zone of inhibition; 1:100 has a 15 mm zone of inhibition; and 1:1000 gives a 0 mm zone of inhibition. For Disinfectant B, a 1:10 dilution gives a 50 mm zone of inhibition; 1:100 has a 25 mm zone of inhibition; and 1:1000 gives a 10 mm zone of inhibition. Which disinfectant is most effective?

A) they are equally effective
B) cannot tell from the information given
C) B
D) A

back 167

B.

front 168

The disk-diffusion test is used to test disinfectants against Staphylococcus aureus. For Disinfectant A, a 1:10 dilution gives a 25 mm zone of inhibition; 1:100 has a 15 mm zone of inhibition; and 1:1000 gives a 0 mm zone of inhibition. For Disinfectant B, 1:10 dilution gives a 50 mm zone of inhibition; 1:100 has a 25 mm zone of inhibition; and 1:1000 gives a 10 mm zone of inhibition. Which disinfectant is bactericidal?

A) they are equally effective
B) A
C) cannot tell from the information given
D) B

back 168

Cannot tell from the information given.

front 169

You inoculate a nutrient agar plate with your fingers after washing your hands with water. Then you wash your hands with bar soap, rinse, and inoculate another nutrient agar plate. You repeat the handwashing with liquid soap and inoculate a third nutrient agar plate. The bar soap and liquid soap have the same chemical formulas. After incubating the plates, you record the amount of bacterial growth on a scale of - (no growth) to 3+ (maximum growth). Your results are: Water alone, +; Bar soap and water, 3+; Liquid soap and water, +. From these data, you can conclude that:

A) bacteria persist on bar soap.
B) soap kills bacteria.
C) liquid soap kills bacteria.
D) water kills bacteria.

back 169

Bacteria persist on bar soap.