9

Question 1

sterilization

Answer 1

In its strictest sense, sterilization refers to the removal or
destruction of all microbes, including viruses and bacterial endospores,
in or on an object. (The term does not apply to prions,
which are infectious proteins, because standard sterilizing techniques
do not destroy them.)
- In practical terms, sterilization indicates only the eradication
of harmful microorganisms and viruses; some innocuous
microbes may still be present and viable in an environment
that is considered sterile.

Question 2

aseptic

Answer 2

describes an environment or procedure

that is free of contamination by pathogens

Question 3

disinfection

Answer 3

refers to the use of physical or chemical
agents known as disinfectants, including ultraviolet light, heat, alcohol, and bleach, to inhibit or destroy microorganisms,
especially pathogens. Unlike sterilization, disinfection does
not guarantee that all pathogens are eliminated; indeed, disinfectants
alone cannot inhibit endospores or some viruses. Further,
the term disinfection is used only in reference to treatment
of inanimate objects.

Question 4

antisepsis

Answer 4

When a chemical is used on skin or other
tissue, the process is called antisepsis3 (an@te@sep´sis), and the
chemical is called an antiseptic. Antiseptics and disinfectants
often have the same components, but disinfectants are more
concentrated or can be left on a surface for longer periods of
time

Question 5

degerming

Answer 5

the removal of microbes from a surface by
scrubbing, such as when you wash your hands or a nurse prepares
an area of skin for an injection. Though chemicals such
as soap or alcohol are commonly used during degerming, the
action of thoroughly scrubbing the surface may be more important
than the chemical in removing microbes.

Question 6

sanitization

Answer 6

the process of disinfecting places and utensils
used by the public to reduce the number of pathogenic microbes
to meet accepted public health standards. Thus, the difference between disinfecting dishes at
home and sanitizing dishes in a restaurant is the arena—private
versus public—in which the activity takes place.

Question 7

pasteurization

Answer 7

the use of heat to kill pathogens and
reduce the number of spoilage microorganisms in food and
beverages.

Question 8

two major types of microbial

control

Answer 8

sterilization, which is the elimination of all
microbes, and antisepsis or disinfection, which each denote the
destruction of vegetative (nonspore) cells and many viruses.
Modifications of disinfection include degerming, sanitization,
and pasteurization

Question 9

-stasis/-static

Answer 9

indicate that a chemical or physical
agent inhibits microbial metabolism and growth but does not
necessarily kill microbes.

Question 10

-cide/-cidal

Answer 10

refer to agents that destroy

or permanently inactivate a particular type of microbe

Question 11

microbial death

Answer 11

the permanent loss of

reproductive ability under ideal environmental conditions.

Question 12

microbial death rate

Answer 12

One technique for evaluating the efficacy of an antimicrobial
agent is to calculate the microbial death rate, which is usually
found to be constant over time for any particular microorganism
under a particular set of conditions

Question 13

There are many types of chemical and physical microbial controls,
but their modes of action fall into two basic categories:

Answer 13

those that disrupt the integrity of cells by adversely altering
their cell walls or cytoplasmic membranes and those that interrupt
cellular metabolism and reproduction by interfering with
the structures of proteins and nucleic acids.

Question 14

hypotonic

Answer 14

surroundings < cell. water go in

Question 15

virus covering

Answer 15

In enveloped viruses, the envelope is a membrane composed
of proteins and phospholipids that is responsible for the
attachment of the virus to its target cell. Damage to the envelope
by physical or chemical agents fatally interrupts viral replication.
The lack of an envelope in nonenveloped viruses accounts
for their greater tolerance of harsh environmental conditions,
including antimicrobial agents.

Question 16

As we have seen, a protein’s function
depends on an exact three-dimensional shape, which is
maintained by

Answer 16

hydrogen and disulfide bonds between amino

acids.

Question 17

ribozyme

Answer 17

that portion of a
ribosome that actually catalyzes the synthesis of proteins is a
ribozyme—that is, an enzymatic RNA molecule. For this reason,
physical or chemical agents that interfere with nucleic
acids also stop protein synthesis.

Question 18

Ideally, agents used for the control of microbes should be

Answer 18

inexpensive,

fast acting, and stable during storage.

Question 19

most resistant microbes

Answer 19

• bacterial endoposres (bacillus, clostiridum) – most resilient forms of life
• mycobacterium (tb)
• protoozoa cysts

Question 20

y mycobacterium resilient

Answer 20

contain a large
amount of a waxy lipid. The wax allows these bacteria to
survive drying and protects them from most water-based
chemicals

Question 21

y cysts resilient

Answer 21

A protozoan cyst’s wall prevents entry
of most disinfectants, protects against drying, and shields
against radiation and heat.

Question 22

high level germicides

Answer 22

kill all pathogens, including
bacterial endospores. Health care professionals use them
to sterilize invasive instruments such as catheters, implants, and
parts of heart-lung machines.

Question 23

intermediat elevel germicides

Answer 23

kill fungal
spores, protozoan cysts, viruses, and pathogenic bacteria but
not bacterial endospores. They are used to disinfect instruments
that come in contact with mucous membranes but are noninvasive,
such as respiratory equipment and endoscopes.

Question 24

low level germicides

Answer 24

Low-level
germicides eliminate vegetative bacteria, fungi, protozoa, and some
viruses; they are used to disinfect items that contact only the skin
of patients, such as furniture and electrodes

Question 25

Temperature and pH affect microbial death rates and the efficacy of antimicrobial methods.

Answer 25

Warm disinfectants, for example, generally work better than cool ones because chemicals react faster at higher temperatures (Figure 9.3). Acidic conditions enhance the antimicrobial effect of heat.

Question 26

bsl 1

Answer 26

suitable for handling microbes, such as E. coli, not known to cause disease in healthy humans. Precautions in BSL-1 are minimal and include hand washing with antibacterial soap and washing surfaces with disinfectants

Question 27

bsl 2

Answer 27

- for handling moderately hazardous agents, such as hepatitis and influenza viruses and methicillin-resistant Staphylococcus aureus - Access to BSL-2 labs is limited when work is being conducted, extreme precautions are taken with contaminated sharp objects, and procedures that might produce aerosols are conducted within safety cabinets

Question 28

bsl 3

Answer 28

- requiring that all manipulations be done within safety cabinets containing high-efficiency particulate air (HEPA) filter - special design features: entry through double sets of doors and ventilation such that air moves into the room only through an open door. Air leaving the room is HEPA-filtered before being discharged outside the room. - designed for experimentation on microbes such as tuberculosis and anthrax bacteria and viruses of yellow fever and Rocky Mountain spotted fever.

Question 29

bsl 4

Answer 29

designated for working with dangerous or exotic microbes that cause severe or fatal diseases in humans, such as Ebola, smallpox, and Lassa fever viruses. BSL-4 labs are either separate buildings or completely isolated from all other areas of their buildings. Entry and exit are strictly controlled through electronically sealed airlocks with multiple showers, a vacuum room, an ultraviolet light room, and other safety precautions designed to destroy all traces of the biohazard. All air and water entering and leaving the facility are filtered to prevent accidental release. Personnel wear “space suits” supplied with air hoses (Figure 9.4). Suits and the laboratory itself are pressurized such that microbes are swept away from workers.

Question 30

thermal death pt

Answer 30

the | lowest temperature that kills all cells in a broth in 10 minutes

Question 31

thermal death time

Answer 31

the time it takes to completely sterilize | a particular volume of liquid at a set temperature

Question 32

deciaml reduction time (D)

Answer 32

When measuring the effectiveness of heat sterilization, researchers calculate the decimal reduction time (D), which is the time required to destroy 90% of the microbes in a sample (Figure 9.5). This concept is especially useful to food processors because they must heat foods to eliminate all the endospores of anaerobic Clostridium botulinum, which could germinate inside sealed cans

Question 33

boiling time

Answer 33

It is impossible to boil something more quickly simply by applying more heat; the added heat is carried away by the escaping steam. Boiling time is the critical factor. Further, it is important to realize that at higher elevations water boils at lower temperatures because atmospheric pressure is lower; thus, a longer boiling time is required in Denver than in Los Angeles to get the same antimicrobial effect.

Question 34

pressure fo rsterilization

Answer 34

Practically speaking, true sterilization using heat requires higher temperatures than that of boiling water. To achieve the required temperature, pressure is applied to boiling water to prevent the escape of heat in steam. The reason that applying pressure succeeds in achieving sterilization is that the temperature at which water boils (and steam is formed) increases as pressure increases

Question 35

autoclave

Answer 35

consists of a pressure chamber, pipes to introduce and evacuate steam, valves to remove air and control pressure, and pressure and temperature gauges to monitor the procedure

Question 36

autoclave conditions

Answer 36

121C, 15 psi f pressure above that of normla air pressure, 15min

Question 37

autoclave bio indicator of sterility

Answer 37

endospores of bacillus stearothermophilus impregnated into tape. After autoclaving, the tape is aseptically inoculated into sterile broth. If no bacterial growth appears, the original material is considered sterile.

Question 38

batch method

Answer 38

Historically, milk was pasteurized | by the batch method for 30 minutes at 63°C

Question 39

flash pasteurization

Answer 39

most milk processors today use a high-temperature, short-time method known as flash pasteurization, in which milk flows through heated tubes that raise its temperature to 72°C for only 15 seconds. This treatment effectively destroys all pathogens.

Question 40

ultra high temp pasteurization

Answer 40

heats the milk to at least 135°C for only 1 second, | but some consumers claim that it adversely affects the taste.

Question 41

ultra high temp sterilization

Answer 41

flash heating milk or other liquids to rid them of all living microbes. The process involves passing the liquid through superheated steam at about 140°C for 1 to 3 seconds and then cooling it rapidly. Treated liquids can be stored indefinitely at room temperature without microbial spoilage, though chemical degradation after months of storage results in flavor changes.

Question 42

ultra high temp sterilization

Answer 42

flash heating milk or other liquids to rid them of all living microbes. The process involves passing the liquid through superheated steam at about 140°C for 1 to 3 seconds and then cooling it rapidly. Treated liquids can be stored indefinitely at room temperature without microbial spoilage, though chemical degradation after months of storage results in flavor changes.

Question 43

moist vs dry heat

Answer 43

- dry heat requires higher temperatures for longer times than moist heat because dry heat penetrates more slowly - water beyter conductor than air

Question 44

hot air

Answer 44

denatures proteins and fosters the oxidation of metabolic and structural chemicals

Question 45

psychrophilic

Answer 45

cold loving

Question 46

fridge n freezing

Answer 46

These processes decrease microbial metabolism, growth, and reproduction because chemical reactions occur more slowly at low temperatures and because liquid water is not available at subzero temperatures.

Question 47

slow freezing

Answer 47

Slow freezing, during which ice crystals have time to form and puncture cell membranes, is more effective than quick freezing in inhibiting microbial metabolism

Question 48

dessication

Answer 48

inhibits microbial growth because | metabolism requires liquid water.

Question 49

lyophilzation

Answer 49

a technique combining freezing and drying, to preserve microbes and other cells for many years. In this process, scientists instantly freeze a culture in liquid nitrogen or frozen carbon dioxide (dry ice); then they subject it to a vacuum that removes frozen water through a process called sublimation, in which the water is transformed directly from a solid to a gas. Lyophilization prevents the formation of large, damaging ice crystals. Although not all cells survive, enough are viable to enable the culture to be reconstituted many years later.

Question 50

membrane filters

Answer 50

Scientists today typically use thin (only 0.1 mm thick), circular membrane filters manufactured of nitrocellulose or plastic and containing specific pore sizes ranging from 25 μm to less than 0.01 μm in diameter (Figure 9.10b). The pores of the latter filters are small enough to trap small viruses

Question 51

osmotic pressure

Answer 51

Another ancient method of microbial control is the use of high concentrations of salt or sugar in foods to inhibit microbial growth by osmotic pressure. The removal of water inhibits cellular metabolism because enzymes are fully functional only in aqueous environments.

Question 52

osmotic pressure limitations

Answer 52

Fungi have a greater ability than bacteria to tolerate hypertonic environments with little moisture

Question 53

electromagnetic radiation

Answer 53

energy without mass traveling in waves at the speed of | light

Question 54

particulate radiation

Answer 54

Particulate radiation consists of high-speed subatomic particles, such as protons, that have been freed from their atoms.

Question 55

ionizing radiation

Answer 55

Electron beams, gamma rays, and some X rays, all of which have wavelengths shorter than 1 nm, are ionizing radiation because when they strike molecules, they have sufficient energy to eject electrons from atoms, creating ions. Such ions disrupt hydrogen bonding, oxidize double covalent bonds, and create highly reactive hydroxyl radicals (see Chapter 6). These ions in turn denature other molecules, particularly DNA, causing fatal mutations and cell death.

Question 56

nonionizing radiation

Answer 56

UV (only this has enough energy), visible, infrared, radio waves. - Electromagnetic radiation with a wavelength greater than 1 nm does not have enough energy to force electrons out of orbit, so it is nonionizing radiation. However, such radiation does contain enough energy to excite electrons and cause them to make new covalent bonds, which can affect the three-dimensional structure of proteins and nucleic acids.

Question 57

UV light

Answer 57

UV light with a wavelength of 260 nm is specifically absorbed by adjacent pyrimidine nucleotide bases in DNA, causing them to form covalent bonds with each other rather than forming hydrogen bonds with bases in the complementary DNA strand (see Figure 7.25). Such pyrimidine dimers distort the shape of DNA, making it impossible for the cell to accurately transcribe or replicate its genetic material. If dimers remain uncorrected, an affected cell may die. - but doesnt penetrate well

Question 58

phenolics

Answer 58

Phenolics are compounds derived from phenol (carbolic acid) molecules that have been chemically modified by the addition of halogens or organic functional groups

Question 59

bisphenolics

Answer 59

Bisphenolics are composed of two covalently linked phenolics

Question 60

phenolics effectiveness

Answer 60

Phenol and phenolics denature proteins and disrupt cell membranes in a wide variety of pathogens. They are effective even in the presence of contaminating organic material, such as vomit, pus, saliva, and feces, and they remain active on surfaces for a prolonged time.

Question 61

alcohols

Answer 61

Alcohols are bactericidal, fungicidal, and virucidal against enveloped viruses; however, they are not effective against fungal spores or bacterial endospores

Question 62

alcohols effectiveness

Answer 62

Alcohols are considered intermediatelevel disinfectants. Isopropanol is slightly superior to ethanol as a disinfectant and antiseptic.

Question 63

Surprisingly, pure alcohol is not an effective antimicrobial | agent because

Answer 63

the denaturation of proteins requires water

Question 64

halogens

Answer 64

Halogens are the four very reactive, nonmetallic chemical elements: iodine, chlorine, bromine, and fluorine.

Question 65

halogens effectiveness

Answer 65

Halogens are intermediate-level antimicrobial chemicals that are effective against vegetative bacterial and fungal cells, fungal spores, some bacterial endospores and protozoan cysts, and many viruses.

Question 66

oxidizing agents

Answer 66

Peroxides, ozone, and peracetic acid kill microbes by oxidizing their enzymes, thereby preventing metabolism. work by releasing oxygen radiclas.

Question 67

oxidizing agents effecgiveness

Answer 67

Oxidizing agents are high-level disinfectants and antiseptics that work by releasing oxygen radicals, which are particularly effective against anaerobic microorganisms. Health care workers use oxidizing agents to kill anaerobes in deep puncture wounds

Question 68

Hydrogen peroxide does not make a good antiseptic for | open wounds because

Answer 68

catalase—an enzyme released from damaged human cells—quickly neutralizes hydrogen peroxide by breaking it down into water and oxygen gas, which can be seen as escaping bubbles.

Question 69

paracetic acid

Answer 69

Peracetic acid is an extremely effective sporicide that can be used to sterilize surfaces.

Question 70

surfactants

Answer 70

Surfactants are “surface active” chemicals. One of the ways surfactants act is to reduce the surface tension of solvents such as water by decreasing the attraction among molecules. One result of this reduction in surface tension is that the solvent becomes more effective at dissolving solute molecules. - soaps, detergents

Question 71

detergents

Answer 71

Synthetic detergents are positively charged organic surfactants that are more soluble in water than soaps.

Question 72

quats

Answer 72

The most popular detergents for microbial control are quaternary ammonium compounds, or quats, which are composed of an ammonium cation (NH4 + ) in which the hydrogen atoms are replaced by other functional groups or hydrocarbon chains

Question 73

quats effectiveness

Answer 73

Quats function by disrupting cellular membranes so that affected cells lose essential internal ions, such as K+. cidal to everything except nonenveloped viruses, mycobacteria, or endospores

Question 74

heavy metal ions

Answer 74

Heavy-metal ions, such as ions of arsenic, zinc, mercury, silver, and copper, are antimicrobial because they combine with sulfur atoms in molecules of cysteine, an amino acid. Such bonding denatures proteins, inhibiting or eliminating their function.

Question 75

heavy metal ions effectiveness

Answer 75

Heavymetal ions are low-level bacteriostatic and fungistatic agents, and with few exceptions their use has been superseded by more effective antimicrobial agents.

Question 76

aldehydes

Answer 76

compounds containing terminal —CHO groups; glutaraldehyde, formaldehyde

Question 77

gaseous agents

Answer 77

bulky items can be sterilized within a closed chamber containing highly reactive microbicidal and sporicidal gases such as ethylene oxide, propylene oxide, and beta-propiolactone

Question 78

antimicrobial enzymes

Answer 78

Many organisms produce chemicals that inhibit or destroy a variety of fungi, bacteria, or viruses. Among these are antimicrobial enzymes, which are enzymes that act against microorganisms.

Question 79

lysozyme

Answer 79

antimicrobial enzyme in human tears that digests the peptidoglycan cell walls of bacteria, causing the bacteria to rupture because of osmotic pressure

Question 80

antimicrobials

Answer 80

Antimicrobials include antibiotics, semisynthetics, and synthetics. - The main difference between these antimicrobials and the chemical agents we have discussed in this chapter is that antimicrobials are typically used for treatment of disease and not for environmental control of microbes.

Question 81

antibiotics

Answer 81

antibiotics are antimicrobial chemicals produced naturally by microorganisms. When scientists chemically modify an antibiotic, the agent is called a semisynthetic. Scientists have also developed wholly synthetic antimicrobial drugs.

Question 82

who popularized phenol

Answer 82

joseph lister; antiseptic during surgery

Question 83

use dilution test

Answer 83

In this test, a researcher dips several metal cylinders into broth cultures of bacteria and briefly dries them at 37°C. The researcher then immerses each contaminated cylinder into a different dilution of the disinfectants being evaluated. After 10 minutes, each cylinder is removed, rinsed with water to remove excess chemical, and placed into a fresh tube of sterile medium for 48 hours of incubation. The most effective agent is the one that entirely prevents microbial growth at the highest dilution

Question 84

use dilution test trivia

Answer 84

- curent standard in US - Some government agencies have expressed concern that the test is neither accurate, reliable, nor relevant so a new one being developed

Question 85

kelsey sykes capacity test

Answer 85

- standard in EU - researchers add a suspension of a bacterium to a suitable concentration of the chemical being tested. Then at predetermined times, they move samples of the mixture into growth medium containing a disinfectant deactivator. After incubation for 48 hours, turbidity in the medium indicates that bacteria survived treatment. Lack of turbidity, indicating lack of bacterial reproduction, reveals the minimum time required for the disinfectant to be effective.

Question 86

Though phenol coefficient, use-dilution, and Kelsey-Sykes capacity tests can be beneficial for initial screening of disinfectants,

Answer 86

they can also be misleading. These types of evaluation are measures of effectiveness under controlled conditions against one or, at most, a few species of microbes, but disinfectants are generally used in various environments against a diverse population of organisms that are often associated with one another in complex biofilms affording mutual protection

Question 87

in-use test

Answer 87

- more realistic, more time consuming - swabs are taken from actual objects, such as operating room equipment, both before and after the application of a disinfectant or an antiseptic. The swabs are then inoculated into appropriate growth media that, after incubation, are examined for microbial growth.