Bio 240 : Chapter 7

Front 1

sterilization

Back 1

removal or destruction of all living microorganisms

0 heating is most common method , which is efficient against endospores

Front 2

sterilizing agent is called a

Back 2

sterilant

Front 3

liquid or gas can be sterilized by

Back 3

filtration

Front 4

commercial sterilization

Back 4

food heated enought to destroy the endospores of clostridumm boulinum

Front 5

control directed at destroying harmful microorgainsms is called

Back 5

disinfection

- usualy refers to destruction of vegetative (non- endospore forming) pathogen

Front 6

________ might make use of chemicals, ultraviolet radiation, boiling water, or steam. In practice, the term is most commonly applied to the use of a chemical (a disinfectant) to treat an inert surface or substance.

Back 6

Disinfection

Front 7

when disinfect is directed at living tissue it is called

Back 7

antisepsis and the chemical is called an antiseptic

Front 8

degerming

Back 8

removal rather than killing of most microbes in a limited area

Front 9

intended to lower microbial counts to safe terms

Back 9

sanitization

Front 10

- cide

Back 10

kill

Front 11

biocide or germicide kills

Back 11

microorganissm (except endospores)

Front 12

fungicide kills

Back 12

fungi

Front 13

virucide

Back 13

inactivates viruses

Front 14

-stat or -stasis

Back 14

stop or to stead

Front 15

once a bacteriostatic agent is removed

Back 15

growth might resume

Front 16

Destruction or removal of all forms of microbial life, including endospores but with the possible exception of prions.

- Usually done by steam under pressure or a sterilizing gas, such as ethylene oxide.

Back 16

sterilization

Front 17

Sufficient heat treatment to kill endospores of Clostridium botulinum in canned food.

- More-resistant endospores of thermophilic bacteria may survive, but they will not germinate and grow under normal storage conditions.

Back 17

commercial sterilization

Front 18

Destruction of vegetative pathogens on inanimate objects.

- May make use of physical or chemical methods.

Back 18

disinfection

Front 19

destruction of vegetative pathogens n living tissue

- Treatment is almost always by chemical antimicrobials.

Back 19

antisepsis

Front 20

Removal of microbes from a limited area, such as the skin around an injection site.

- Mostly a mechanical removal by an alcohol-soaked swab.

Back 20

degerming

Front 21

Treatment is intended to lower microbial counts on eating and drinking utensils to safe public health levels.

- May be done with high-temperature washing or by dipping into a chemical disinfectant.

Back 21

sanitization

Front 22

aseptic meanas

Back 22

object or area is free of pathogens

Front 23

absence of significant contamination

Back 23

asepsis

Front 24

factors that influence the effectiveness of antimicrobial treatments

Back 24

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

● Environmental influences. Most disinfectants work somewhat better in warm solutions.

Front 25

The more microbes there are to begin with,

Back 25

the longer it takes to eliminate the entire population.

Front 26

Most disinfectants work somewhat better in

Back 26

warm solutions.

Front 27

plotting the typical microbial death curve logarithmically results ins a

Back 27

straight line

Front 28

medium rich in fats and proteins

Back 28

protects microbes

- makes them have a higher survival rate

Front 29

plotting the typical microbial death curve arithmetically

Back 29

is impractical

Front 30

if rate of killing is the same it will take longer to kill

Back 30

all members of a larger population

Front 31

- Bacterial populations usually die at a constant rate when heated or when treated with antimicrobial chemicals.

- It is necessary to use logarithmic numbers to graph bacterial populations effectively.

- Understanding logarithmic death curves for microbial populations, including the elements of time and the size of the initial population, is especially useful in food preservation and in the sterilization of media or medical supplies.

Back 31

ya

Front 32

damage to the lipids or proteins of the plasma membrane by antimicrobial agents causes

Back 32

cellular contents to leak into the surrounding medium and interferes with the growth of the cell

Front 33

desiccation through lyophilization

Back 33

drying

- microorganisms cannot grow or reproduce but can remian viable for years. when water is available hey can contiue to grow and divide

Front 34

osmotic pressure

Back 34

use of high concentrations of salts and sugars

- creates hypertonic environment which causes water to leave the microbial cell which denies the moisture needed to grow

Front 35

Heat appears to kill microorganisms by

Back 35

denaturing their enzymes; the resultant changes to the three-dimensional shapes of these proteins inactivate them

Front 36

thermal death point TDP

Back 36

the lowest temperature at which all the microorganisms in a particular liquid suspension will be killed in 10 minutes.

Front 37

thermal death time (TDT),

Back 37

the minimal length of time for all bacteria in a par- ticular liquid culture to be killed at a given temperature.

Front 38

TDP and tdt INDICATE

Back 38

severity of treatment required to kill a gien population of bacteria

Front 39

Decimal reduction time DRT

Back 39

DRT is the time, in minutes, in which 90% of a population of bacteria at a given temperature will be killed

Front 40

Moist heat kills microorganisms primarily by

Back 40

coagulating proteins (denaturation)

Front 41

bried boiling will kill

Back 41

most pathogens

Front 42

Autoclaving is the preferred method of sterilization in health care environments, unless the material to be sterilized can be damaged by heat or moisture. The higher the pressure in the autoclave, the higher the temperature.

Back 42

ya

Front 43

steam at a pressure of about _____________ will kill all organisms (but not prions; see page 195) and their endospores in about 15 minutes.

Back 43

15 psi (121°C)

Front 44

large indutrial autoclabes are called

Back 44

retorts

Front 45

steam cant penetrate

Back 45

aluminum foil

Front 46

pasteurization

Back 46

to eliminate pathogenic microbes and lower microbial numbers

- thermoduric surivive pasteriuzation- unlikely to cause disease

Front 47

thermoduric

Back 47

heat resistant bacteria

Front 48

phosphatase test

Back 48

whether products have been pasteurized

- if pasterized, phosphatase is inactivated

Front 49

high- temperature short-time (HTST) pasteurization, is applied as the milk flows continuously past a heat exchanger

Back 49

at least 72 c for 15 sec

Front 50

ultra high temperature treatments UHT

Back 50

sterilization, refrigeration not needed

Front 51

equivalent treatments:

Back 51

as the temperature is in- creased, much less time is needed to kill the same number of microbes.

Front 52

Dry heat kills by

Back 52

oxidation effects

Front 53

One of the simplest methods of dry heat sterilization is

Back 53

direct flaming.

Front 54

_________ is the passage of a liquid or gas through a screenlike material with pores small enough to retain microorganisms

- used to sterilize heat sensitive materials, media, enzymes, vaccines, and antibiotic solutions

Back 54

Filtration

Front 55

High-efficiency particulate air (HEPA) filters remove

Back 55

almost all microorganisms larger than about 0.3 μm in diameter.

Front 56

membrane filters composed of

Back 56

cellulose esters or plastic polymers

- These filters are only 0.1 mm thick. The pores of membrane filters, for example, 0.22-μm and 0.45-μm sizes, are intended for bacteria. Some very flexible bacteria, such as spirochetes, or the wall-less mycoplasma, will sometimes pass through such filters, however. Filters are available with pores as small as 0.01 μm, a size that will retain viruses and even some large protein molecules.

Front 57

pathogenic bacteria generally will not growh at refrigerator temperatures but _____ is an important exception

Back 57

listeria

Front 58

Radiation that kills microorganisms (sterilizing radiation) is of two types:

Back 58

ionizing and nonionizing

Front 59

_______________gamma rays, X rays, and high-energy electron beams—has a wavelength shorter than that of nonionizing radiation, less than about 1 nm. Therefore, it carries much more energy

Back 59

ionizing radiation

Front 60

Ionizing radiation, especially high-energy electron beams, is used to sterilize

Back 60

pharmaceuticals and disposable dental and medical supplies, such as plastic syringes, surgical gloves, suturing materials, and catheters.

Front 61

Nonionizing radiation has a wavelength _________than that of ionizing radiation, usually greater than about 1 nm.

Back 61

longer

Front 62

The best example of nonionizing radiation is

Back 62

ultraviolet (UV) light. UV light damages the DNA of exposed cells by causing bonds to form between adjacent pyrimidine bases, usually thymines, in DNA chains

Front 63

Microwaves do not have much direct effect on microorgansms, and bacteria can readily be isolated from the interior of recently operated microwave ovens. Moisture-containing foods are heated by microwave action, and the heat will kill most vegetative pathogens.

Back 63

ya

Front 64

moist heat 2 methods

Back 64

boiling or flowing steam and autoclabing

Front 65

boiling or flowing steam

Back 65

- protein denaturation

- Kills vegetative bacterial and fungal pathogens and almost all viruses within 10 min; less effective on endospores.

- dishes

Front 66

autoclaving

Back 66

- protein denaturation

- Very effective method of sterilization; at about 15 psi of pressure (121°C), all vegetative cells and their endospores are killed in about 15 min.

Front 67

pasteurization

Back 67

- protein denaturation

- Heat treatment for milk (72°C for about 15 sec) that kills all pathogens and most nonpathogens.

- milk, beer and wine

Front 68

dry heat 3 methods

Back 68

direct flaming, incineration, hot air sterilzation

Front 69

direct flaming

Back 69

- burning contaminants to ashes

- Very effective method of sterilization.

- innoculating loops

Front 70

incineration

Back 70

- burning to ashes

- Very effective method of sterilization.

Front 71

hot air sterilization

Back 71

- oxidation

- Very effective method of sterilization. but requires temp of 170 c for about 2 hr

- glasswear

Front 72

filtration

Back 72

- seperation of bacteria from suspending liquid

- Removes microbes by passage of a liquid or gas through a screenlike material; most filters in use consist of cellulose acetate or nitrocellulose.

- Useful for sterilizing liquids (e.g., enzymes, vaccines) that are destroyed by heat

Front 73

heat methods used to control microbial growth

Back 73

- moist heat (boiling and autoclaving)

- pasteurization

- dry heat (direct flaming, incineration, hot air sterilization)

Front 74

cold methods used to control microbial growth

Back 74

- refrigeration

- deep freezing

- lyophilization

Front 75

refrigeration

Back 75

- Decreased chemical reactions and possible changes in proteins

- has a bacteriostatic effect

- food, drug preservation

Front 76

deep freezing

Back 76

- Decreased chemical reactions and possible changes in proteins

- An effective method for preserving microbial cultures, in which cultures are quick- frozen between − 50° and − 95°C.

Front 77

lyophilization

Back 77

- Decreased chemical reactions and possible changes in proteins

- Most effective method for long-term preservation of microbial cultures; water removed by high vacuum at low temperature.

Front 78

high pressure

Back 78

- alteration of molecular structure of proteins and carbohydrates

- preserves colors, flavors, nutrent values

- juices

Front 79

dessication

Back 79

- disruption of metabolism

- involves removing water from microbes; primarily bacteriostatic

Front 80

osmotic pressure

Back 80

- plasmolysis

- results in loss of water from microbial cells

Front 81

radiation methods used to control microbial growth

Back 81

ionizing and nonionizing

Front 82

ionizing radiation

Back 82

- destruction of dna

- not widespread in routine steriliztion

- sterilizing pharmaceuticals and medical and dental supplies

Front 83

nonionizing radiation

Back 83

- damage to dna

- radiation is not very penetrating

- control of closed environment with uv ( germicidal ) lamp

Front 84

___________is used in teaching laboratories to evaluate the efficacy of a chemical agent.

Back 84

disk-diffusion method

Front 85

lister was the first to use

Back 85

phenol ( carbolic acid )

- control surgical infections in the operating room

Front 86

derivatives of phenol called phenolics contain a molecule of

Back 86

phenol that has been chemically altered to reduce its irritating qualitites or increase its antibacterial activity in combination with a soap or detergent

Front 87

Phenolics exert antimicrobial activity by

Back 87

injuring lipid-containing plasma membranes, which results in leakage of cellular contents.

Front 88

bisphenols

Back 88

derivatives of phenol that contain two phonlic groups connected by a bridge

Front 89

Triclosan

- bisphenol

Back 89

inhibits an enzyme needed for the biosynthesis of fatty acids (lipids), which mainly affects the integrity of the plasma membrane.

- especially effective against gram-positive bacteria, yeasts, and gram - negative bacteria

- not effective against pseudomonas aeruginosa

Front 90

__________ have a broad spectrum of activity, with a mode of action primarily affecting bacterial cell membranes. They are especially effective against gram-positive bacteria. Biguanides are also effective against gram-negative bacteria, with the significant exception of most pseudomonads. Biguanides are not sporicidal but have some activity against enveloped viruses

- ex. chlorhexidine

Back 90

Biguanides

Front 91

halogens, particularly____________, are effective antimicrobial agents, both alone and as constituents of inorganic or organic compounds.

Back 91

iodine and chlorine

Front 92

Iodine (I2) is one of the oldest and most effective antiseptics. It is active against all kinds of bacteria, many endospores, various fungi, and some viruses.

Iodine impairs protein synthesis and alters cell membranes, apparently by forming complexes with amino acids and unsaturated fatty acids.

Back 92

ya

Front 93

tincture

Back 93

solution in acqueous alcohol

Front 94

iodophor

Back 94

combination of iodine and organic molecule where iodine is realeased slowly

- do not stain and are less irritating

Front 95

chlorine has germicidal action caused by

Back 95

hypochlorous acid HOCl that forms when chlorine is added to water

Front 96

Hypochlorite is a strong oxidizing agent that prevents much of the cellular enzyme system from functioning. Hypochlorous acid is the most effective form of chlorine because it is neutral in electri- cal charge and diffuses as rapidly as water through the cell wall.

Back 96

ya

Front 97

chloramines

Back 97

combinations of chlirne and ammonia

-toxic to acquarium fish

- relatively effective in organic matter but have the disadvantages ofacting more slowly and being less effective than hypochlorite.

Front 98

__________effectively kill bacteria and fungi but not endospores and nonenveloped viruses.

Back 98

Alcohols

Front 99

_______ usually denatures protein, but it can also disrupt membranes and dissolve many lipids, including the lipid component of enveloped viruses.

Back 99

Alcohol

Front 100

Two of the most commonly used alcohols are

Back 100

ethanol and isopropanol.

- The recommended optimum concentration of ethanol is 70%, but concentrations between 60% and 95% seem to kill as well

- pure ethanol is less effective than aqueous solutions because denaturation requires water

Front 101

viruses that lack a lipid envelop are resistant to

Back 101

alcohol based hand sanitizers

Front 102

The ability of very small amounts of heavy metals, especially silver and copper, to exert antimicrobial activity is referred to as

Back 102

oligodynamic action

- When the metal ions combine with the sulfhydryl groups on cellular proteins, denaturation results.

Front 103

surface active agents or surfactants cand

Back 103

decrease surface tension among molecules of a liquid

- soap and detergents

Front 104

Soap breaks the oily film into tiny droplets, a process called _________, and the water and soap together lift up the emulsified oil and debris and float them away as the lather is washed off.

Back 104

emulsification

Front 105

Acid-anionic sanitizers are very important in cleaning food-processing facilities, especially dairy utensils and equipment. They are usually combinations of phosphoric acid with a surface-active agent. Their sanitizing ability is related to the negatively charged portion (anion) of the molecule, which reacts with the plasma membrane.

Back 105

ya

Front 106

The most widely used surface-active agents are the cationic detergents, especially the ________

- especially bactericidal against gram positive bacteria

- fungicidal, embicidal, and virucidal against enveloped viruses

- they do not kill endospores or mycobacteria

- change the cells permeability and cuase the loss of essentiaal cytoplasmic consitutents such as potassium

- pseudomonas survive and grow in quats

Back 106

quaternary ammonium compounds (quats).

Front 107

Their name is derived from the fact that they are modifications of the four-valence ammonium ion, NH4+

Back 107

quats

Front 108

Chemical preservatives are frequently added to

Back 108

foods to retard spoilage.

- Sulfur dioxide (SO2) has long been used as a disinfectant, especially in wine-making.

Front 109

There has been some concern that the reaction of nitrites with amino acids can form certain carcinogenic products known as

Back 109

nitrosamines

Front 110

Aldehydes are among the most effective antimicrobials. Two examples are

Back 110

formaldehyde and glutaraldehyde.

Front 111

the gaseous chemosterilants are frequently used as

Back 111

substitutes for physical sterilization processes.

Front 112

plasma

Back 112

- fourth state of matter where gas is excited by an electromagentic field to make a mixutre of nuclei with assortedelectrical charges adn free elctrons

Front 113

plasmas have many free radicals that quickly destroy

Back 113

endospore forming microbes

- requires only low tempreratures

Front 114

The use of supercritical fluids in sterilization combines

Back 114

chemical and physical methods.

- When carbon dioxide is compressed into a “supercritical” state, it has properties of both a liquid (with increased solubility) and a gas (with a lowered surface tension).

Front 115

Peroxygens are a group of oxidizing agents that includes

Back 115

hydrogen peroxide and peracetic acid.

Front 116

Although ozone is a more effective killing agent than chlorine, its residual activity is

Back 116

difficult to maintain in water.

Front 117

Many biocides tend to be more effective against

Back 117

gram-positive bacteria, as a group, than against gram-negative bacteria.

-A principal factor in this relative resistance to biocides is the negative bacteria

Front 118

bacterial endospores are affected by relatively few

Back 118

biocides

Front 119

The resistance of viruses to biocides largely depends on the presence or absence of __________

Back 119

an envelope.

Front 120

Antimicrobials that are lipid- soluble are more likely to be effective against

Back 120

enveloped viruses.

Front 121

Nonenveloped viruses, which have only a protein coat, are more

Back 121

resistant—fewer biocides are active against them.

Front 122

to destroy prions

Back 122

combined use of a solution of sodium hydroxide and autoclaving at 134°C.

Front 123

phenol

Back 123

- Disruption of plasma membrane, denaturation of enzymes.

- rarely used, used for comparison, irritating qualities

Front 124

phenolics

Back 124

- Disruption of plasma membrane, denaturation of enzymes.

- environmental surfaces, instruments, skin surfaces, mucous membranes

- derivative of phenol that is reactive even in the presence of organic material

Front 125

bisphenols

Back 125

- probably disruption of plasma membrane

- disinfectant hand soaps and skin lotions

- triclosan

- broad spectrum

- most effective against gram positives

Front 126

bisguanides (chlorhexidine)

Back 126

- disruption of plasma membrane

- skin disinfection

- Bactericidal to gram-positives and gram- negatives; nontoxic, persistent.

Front 127

halogens

Back 127

- Iodine inhibits protein function and is a strong oxidizing agent; chlorine forms the strong oxidizing agent hypochlorous acid, which alters cellular components.

- Iodine is an effective antiseptic available as a tincture and an iodophor; chlorine gas is used to disinfect water; chlorine compounds are used to disinfect dairy equipment, eating utensils, household items, and glassware.

Front 128

alcohols

Back 128

- protein denaturation and lipid dissolution

- Bactericidal and fungicidal, but not effective against endospores or nonenveloped viruses; commonly used alcohols are ethanol and isopropanol.

Front 129

heavy metals and their compounds

Back 129

- denaturation of enzymes and other essential proteins

- Silver nitrate may be used to prevent ophthalmia neonatorum; silver-sulfadiazine is used as a topical cream on burns; copper sulfate is an algicide.

- Heavy metals such as silver and mercury are biocidal.

Front 130

surface active agents

Back 130

- soap and detergents

- acid anionic sanitizers

- quaternary ammonium compounds ( cationic detergents )

Front 131

soap and detergents

Back 131

- mechanical removal of microbes through scrubbing

- skin degerming and removal of debris

Front 132

acid anionic sanitizers

Back 132

- may involve enzyme inactivation or disruption

- sanitzers in dairy and food processing industires

Front 133

quaternary ammonium compounds ( cationic detergents )

Back 133

- enzyme inhibition, protein denaturation, disruption of plasma membranes

- antiseptic for sking, instruments, rubber goods

- Bactericidal, bacteriostatic, fungicidal, and virucidal against enveloped viruses. Examples of quats are Zephiran and Cepacol.

Front 134

Organic acids

Back 134

- Metabolic inhibition, mostly affecting molds; action not related to their acidity.

- used to control mold and some bacteria

Front 135

nitrates/ nitrites

Back 135

- Active ingredient is nitrite, which is produced by bacterial action on nitrate. Nitrite inhibits certain iron- containing enzymes of anaerobes.

- Prevents growth of Clostridium botulinum in food; also imparts a red color

Front 136

aldehydes

Back 136

- protein denaturation

- Glutaraldehyde (Cidex) is less irritating than formaldehyde and is used for disinfecting medical equipment.

- very effective antimicrobials

Front 137

chemical sterilization = ehtylene oxide and other gaseous sterilants

Back 137

- inhibits bital cellular functions

- sterilization of materials that would be damaged by heat

Front 138

Plasma sterilization

Back 138

- inhibits bital cellular functions

- tubular medical instruments

- Usually hydrogen peroxide excited in a vacuum by an electromagnetic field.

Front 139

supercritical fluids

Back 139

- inhibits vital celluar functions

- sterilizing organic medical implants

- carbon dioxide compressed to a supercritical state

Front 140

peroxygens and other forms of oxygen

Back 140

- oxidation

- deep wounds

- Ozone is widely used as a supplement for chlorination; hydrogen peroxide is a poor antiseptic but a good disinfectant. Peracetic acid is especially effective.

Front 141

The control of microbial growth can prevent

Back 141

infections and food spoilage

Front 142

Sterilization is the process of

Back 142

removing or destroying all microbial life on an object.

Front 143

Commercial sterilization is heat treatment of

Back 143

canned foods to destroy C. botulinum endospores.

Front 144

Disinfection is the process of

Back 144

reducing or inhibiting microbial growth on a nonliving surface.

Front 145

Antisepsis is the process of

Back 145

reducing or inhibiting microorganisms on living tissue.

Front 146

The suffix -cide means to_______; the suffix -stat means to inhibit.

Back 146

-cide = kill

Front 147

Sepsis is

Back 147

bacterial contamination.

Front 148

Bacterial populations subjected to _____________ usually die at a constant rate

Back 148

heat or antimicrobial chemicals u

Front 149

Such a death curve, when plotted logarithmically, shows this constant death rate as

Back 149

a straight line.

Front 150

The time it takes to kill a microbial population is proportional to

Back 150

the number of microbes.

Front 151

__________ have different susceptibilities to physical and chemical controls.

Back 151

Microbial species and life cycle phases (e.g., endospores)

Front 152

_________may interfere with heat treatments and chemical control agents.

Back 152

Organic matter

Front 153

Longer exposure to lower heat can produce the same effect as

Back 153

shorter time at higher heat.

Front 154

The susceptibility of the plasma membrane is due to its

Back 154

lipid and protein components.

Front 155

Certain chemical control agents damage the plasma membrane by altering its

Back 155

permeability.

Front 156

Some microbial control agents damage cellular proteins by

Back 156

breaking hydrogen bonds and covalent bonds.

Front 157

Heat is frequently used to

Back 157

kill microorganisms.

Front 158

Moist heat kills microbes by

Back 158

denaturing enzymes.

Front 159

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

Back 159

Thermal death point (TDP)

Front 160

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

Back 160

Thermal death time (TDT)

Front 161

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

Back 161

Decimal reduction time (DRT)

Front 162

Boiling (100°C) kills many vegetative cells and viruses within

Back 162

10 minutes.

Front 163

_________is the most effective method of moist heat sterilization. The steam must directly contact the material to be sterilized.

Back 163

Autoclaving (steam under pressure)

Front 164

In ___________, a high temperature is used for a short time (72°C for 15 seconds) to destroy pathogens without altering the flavor of the food.

Back 164

HTST pasteurization

Front 165

____________ (140°C for 4 seconds) is used to sterilize dairy products.

Back 165

Ultra-high-temperature (UHT) treatment

Front 166

Methods of dry heat sterilization include

Back 166

direct flaming, incineration, and hot-air sterilization. Dry heat kills by oxidation.

Front 167

Different methods that produce the same effect (reduction in microbial growth) are called

Back 167

equivalent treatments.

Front 168

Filtration is the

Back 168

passage of a liquid or gas through a filter with pores small enough to retain microbes.

Front 169

Microbes can be removed from air by

Back 169

high-efficiency particulate air (HEPA) filters.

Front 170

Membrane filters composed of cellulose esters are commonly used to filter out

Back 170

bacteria, viruses, and even large proteins.

Front 171

Most microorganisms do not reproduce at ordinary refrigerator temperatures (0–7°C).

- Many microbes survive (but do not grow) at the subzero temperatures used to store foods.

Back 171

ya

Front 172

High pressure denatures proteins in

Back 172

vegetative cells.

Front 173

In the absence of water,

Back 173

microorganisms cannot grow but can remain viable.

Front 174

__________ can resist desiccation.

Back 174

Viruses and endospores

Front 175

Microorganisms in high concentrations of salts and sugars undergo

Back 175

plasmolysis.

Front 176

Molds and yeasts are more capable than bacteria of growing in materials with

Back 176

low moisture or high osmotic pressure.

Front 177

The effects of radiation depend on its

Back 177

wavelength, intensity, and duration.

Front 178

___________ (gamma rays, X rays, and high-energy electron beams) has a high degree of penetration and exerts its effect primarily by ionizing water and forming highly reactive hydroxyl radicals.

Back 178

Ionizing radiation

Front 179

_____________, a form of nonionizing radiation, has a low degree of penetration and causes cell damage by making thymine dimers in DNA that interfere with DNA replication; the most effective germicidal wavelength is 260 nm.

Back 179

Ultraviolet (UV) radiation

Front 180

Microwaves can kill microbes indirectly as materials get hot.

Back 180

ya

Front 181

Chemical agents are used on living tissue (as ___________) and on inanimate objects (as __________).

Back 181

living tissue (as antiseptics) and on inanimate objects (as disinfectants).

Front 182

Few chemical agents achieve sterility.

Back 182

ya

Front 183

The presence of organic matter, degree of contact with microorganisms, and temperature should also be considered.

Back 183

in disinfection

Front 184

in the ______________ test, bacterial survival in the manufacturer’srecommended dilution of a disinfectant is determined.

Back 184

In the use-dilution test

-Viruses, endospore-forming bacteria, mycobacteria, and fungi can also be used in the use-dilution test.

Front 185

In the __________ method, a disk of filter paper is soaked with a chemical and placed on an inoculated agar plate; a zone of inhibition indicates effectiveness.

Back 185

disk-diffusion method

Front 186

Phenolics exert their action by

Back 186

injuring plasma membranes.

Front 187

__________such as triclosan (over the counter) and hexachloro- phene (prescription) are widely used in household products.

Back 187

Bisphenols

Front 188

Biguanides damage

Back 188

plasma membranes of vegetative cells

Front 189

Some____________ are used alone or as components of inorganic or organic solutions.

Back 189

halogens (iodine and chlorine)

Front 190

Iodine may combine with certain amino acids to

Back 190

inactivate enzymes and other cellular proteins.

Front 191

Iodine is available as a tincture (___________) or as an iodophor (____________).

Back 191

tincture (in solution with alcohol) or as an iodophor (combined with an organic molecule).

Front 192

The germicidal action of chlorine is based on the formation of

Back 192

hypochlorous acid when chlorine is added to water.

Front 193

Alcohols exert their action by

Back 193

denaturing proteins and dissolving lipids.

Front 194

In tinctures, alcohols enhance the

Back 194

effectiveness of other antimicrobial chemicals.

Front 195

Aqueous ethanol (60–95%) and isopropanol are used as

Back 195

disinfectants.

Front 196

Silver, mercury, copper, and zinc exert their antimicrobial action through

Back 196

oligodynamic action. When heavy metal ions combine with sulfhydryl (—SH) groups, proteins are denatured.

Front 197

________have limited germicidal action but assist in removing microorganisms.

Back 197

Soaps

Front 198

Acid-anionic detergents are used to

Back 198

clean dairy equipment.

Front 199

_________ are cationic detergents attached to NH4+.

Back 199

Quats

Front 200

By disrupting plasma membranes, quats allow

Back 200

cytoplasmic constituents to leak out of the cell.

Front 201

Quats are most effective against

Back 201

gram-positive bacteria.

Front 202

SO2, sorbic acid, benzoic acid, and propionic acid inhibit

Back 202

fungal metabolism and are used as food preservatives.

Front 203

Nitrate and nitrite salts prevent

Back 203

germination of C. botulinum endospores in meats.

Front 204

Nisin and natamycin are antibiotics used to

Back 204

preserve foods, especially cheese.

Front 205

Aldehydes such as formaldehyde and glutaraldehyde are among the most effective

Back 205

chemical disinfectants. They exert their antimicrobial effect by inactivating proteins.

Front 206

Ethylene oxide is the gas most frequently used for

Back 206

sterilization.

- It penetrates most materials and kills all microorganisms by protein denaturation.

Front 207

Free radicals in plasma gases are used to

Back 207

sterilize plastic instruments.

Front 208

Supercritical fluids, which have properties of ____________, can sterilize at low temperatures.

Back 208

liquid and gas, can sterilize at low temperatures.

Front 209

Hydrogen peroxide, peracetic acid, benzoyl peroxide, and ozone exert their antimicrobial effect by

Back 209

oxidizing molecules inside cells.

Front 210

Gram________ bacteria are generally more resistant than gram __________ bacteria to disinfectants and antiseptics.

Back 210

-negative are more resistant that -positive bacteria to disinfectants and antiseptics

Front 211

Mycobacteria, endospores, and protozoan cysts and oocysts are

Back 211

very resistant to disinfectants and antiseptics.

Front 212

_________ viruses are generally more resistant than __________ viruses to disinfectants and antiseptics.

Back 212

Nonenveloped viruses are more resistant than enveloped viurses to disinfectants and antiseptics

Front 213

Prions are resistant to

Back 213

disinfection and autoclaving.

Front 214

Which of the following is most effective for sterilizing mattresses and plastic Petri dishes?

a. chlorine

b. ethylene oxide

c. glutaraldehyde

d. autoclaving

e. nonionizing radiation

Back 214

b. ethylene oxide

Front 215

Which of these disinfectants does not act by disrupting the plasma membrane?

a. phenolics

b. phenol

c. quats

d. halogens

e. biguanides

Back 215

d. halogens

Front 216

Which of the following cannot be used to sterilize a heat-labile solution stored in a plastic container?

a. gamma radiation

b. ethylene oxide

c. supercritical fluids

d. autoclaving

e. short-wavelength radiation

Back 216

d. autoclaving

Front 217

Which of the following is used to control microbial growth in foods?

a. organic acids

b. alcohols

c. aldehydes

d. heavy metals

e. all of the above

Back 217

a. organic acids

Front 218

Which disinfectant is the most effective?

Back 218

a

Front 219

Which disinfectant(s) is (are) bactericidal?

a. A, B, C, and D

b. A, C, and D

c. A only

d. B only

e. none of the above

Back 219

b. A, C, and D

Front 220

Which of the following is not a characteristic of quaternaryammonium compounds?

a. bactericidal against gram-positive bacteria

b. sporicidal

c. amoebicidal

d. fungicidal

e. kills enveloped viruses

Back 220

b. sporicidal

Front 221

A classmate is trying to determine how a disinfectant might kill cells. You observed that when he spilled the disinfectant in your reduced litmus milk, the litmus turned blue again. You suggest to your classmate that

a. the disinfectant might inhibit cell wall synthesis.

b. the disinfectant might oxidize molecules.

c. the disinfectant might inhibit protein synthesis.

d. the disinfectant might denature proteins.

e. he take his work away from yours.

Back 221

b. the disinfectant might oxidize molecules.

Front 222

Which of the following is most likely to be bactericidal?

a. membrane filtration

b. ionizing radiation

c. lyophilization(freeze-drying)

d. deep-freezing

e. all of the above

Back 222

b. ionizing radiation

Front 223

Variables that affect determination of the thermal death point are

Back 223

■ The innate heat resistance of the strain of bacteria

■ The past history of the culture, whether it was freeze-dried, wetted, etc.

■ The clumping of the cells during the test

■ The amount of water present

■ The organic matter present

■ Media and incubation temperature used to determine viability of the culture after heating

Front 224

which of the following does not kill endospores?

a. autoclaving

b. incineration

c. hot-air sterilization

d. pasteurization

e. All of the above killendospores.

Back 224

d. pasteurization

Front 225

Ig

Back 225

Immunoglobulin

Front 226

IgG vs IgM

Back 226

heavy chains are different

Front 227

IgG is

Back 227

serious

- 80% of your protection

- cross placenta

- gamma chain

Front 228

IgM

Back 228

first antibodies made

- mu chain

Front 229

IgA

Back 229

- alpha chain

Front 230

IgE

Back 230

built like normal monomer

- epsilon chain

- involved in allergies

Front 231

IgD

Back 231

- delta chain

Front 232

- variable region (ends) where

Back 232

binds with antigen

Front 233

b cell makes

Back 233

makes antibody

Front 234

helper t cell

Back 234

defined by presence of antigen CD4 on their membranes

- cd4 picks up information and sends it to interleuken

Front 235

Tc (CD8)

Back 235

cytotokic t cells

- when they find target the produce emzyme that kills cell membrane causes cell lysis

Front 236

antigen presenting cells (APC)

Back 236

- dentric cells

- macrophages

- when cell injests nd then digest then bacterial antigen is now on its surface, can then be recognized by helper t cell

Front 237

T independent antigen

Back 237

interferes with b cell without t cell involvement

Front 238

T dependent antigen

Back 238

depends on t cells to interfere with b cells

Front 239

antibody coated cells are targeted by

Back 239

cytotoxic cells

Front 240

b memory cells

Back 240

formed within germinal centers following primary infection and are important in generating an accelerated and more robust antibody-mediated immune response in the case of re-infection

- secondary immune response

- naturally acquired active immunity

Front 241

artificially acquired active immunity

Back 241

vaccination

Front 242

artificially acquired passive immunity

Back 242

injection of antibodies

- lasts short period of time, but is immediate treatment

- not made in body

Front 243

pasteur

Back 243

injected rabies in horse and isolated the serum

- required daily injections for 14-21 days (small doses)

Front 244

naturally acquire passive

Back 244

across the placenta IgG antibodies transfered

- dont last longer than 6 months because they are proteins that you dont make

Front 245

using antibodies

Back 245

- to identify bacteria and viruses (direct)

(if bacterium and antibodies will combine and will agglutinate)

- to test for pregnancy (presence of HCG)

Front 246

boosters are composed of

Back 246

antigens

Front 247

serotype

Back 247

a distinct variation within a species of bacteria or virus or among immune cells of different individuals.

Front 248

fetus produces hormone called

Back 248

HCG prevents shedding of uterine lining prevents menstruation

- injecting with HCG is fertility drug

- pregnancy strip is antiHCG

Front 249

if antigens are produced

Back 249

have the antibodies either because they are currently infected, had it and made antibodies, or got vaccinated

Front 250

seroconvert

Back 250

negative then positive

- got infection

Front 251

if titer increases

Back 251

it means you have an active infection

Front 252

if titer is consistant

Back 252

means you have antibodies present but not infected

Front 253

if igm present

Back 253

you have infection because igm are produced first

Front 254

-mab

Back 254

monoclonal antibodies

Front 255

why cant you grow eukaryotic cells for long

Back 255

bc they have membranes bound organelles

Front 256

monoclonal antibodies

Back 256

immunotoxins: MAB conjugated with a toxin to target cancer cells

- chimeric MABs: genetically modified mice that produce Ab with a human constant region

- humanized MABs: MABs that are mostly human except for mouse antigen binding

- fully humanized MABS