Deck 9: Controlling Microbial Growth in the Environment

Question 1

Which of the following types of radiation causes the formation of damaging chemical bonds in DNA?

A) infrared radiation
B) microwaves
C) X-rays
D) ultraviolet light
E) gamma rays

Answer 1

D

Question 2

A stationary broth culture contains 10 billion (1010) cells. The microbial death rate during autoclaving of this spent culture is 1.5 minutes. How long must it be autoclaved to be considered sterile?

A) 10 minutes
B) 12 minutes
C) 20 minutes
D) 9 minutes
E) 16.5 minutes

Answer 2

E

Question 3

Which of the following is the most appropriate pairing of microbe and biosafety level?

A) anthrax, BSL-1
B) Ebola, BSL-2
C) methicillin-resistant Staphylococcus aureus (MRSA), BSL-2
D) E. coli, BSL-3
E) tuberculosis, BSL-1

Answer 3

C

Question 4

A germistatic agent would be effective on

A) vegetative bacterial cells.
B) nonenveloped viruses.
C) protozoal cysts.
D) fungus spores.
E) bacterial endospores.

Question 5

An instrument that will come into contact with only the skin of a patient should be disinfected with a(n)

A) intermediate-level germicide.
B) degerming agent only.
C) germistatic agent only.
D) low-level germicide.
E) high-level germicide.

Question 6

Antimicrobial agents that damage nucleic acids also affect

A) the cell wall.
B) the cell membrane.
C) the viral envelope.
D) protein synthesis.
E) endospores.

Question 7

Filtration is a(n) method of achieving sterilization.

A) antiseptic
B) germistatic
C) viricidal
D) germicidal
E) degerming

Question 8

Seventy-percent alcohol is effective against

A) protozoan cysts.
B) prions.
C) nonenveloped viruses.
D) bacterial endospores.
E) enveloped viruses.

Question 9

An antimicrobial agent that will have the most lasting germicidal effect.

A) damages DNA
B) damages cytoplasmic membranes
C) inhibits enzymatic activity
D) damages cell walls
E) destroys metabolites

Question 10

The individual serving of half & half used in restaurants is usually treated by

A) autoclaving.
B) lyophilization.
C) filtration.
D) ultra-high-temperature sterilization.
E) ionizing radiation.

Question 11

Which of the following is a target of pasteurization?

A) Chlamydia trachomatis
B) Clostridium botulinum
C) Bacillus stearothermophilus
D) Neisseria gonorrhoeae
E) Brucella melitensis

Question 12

Which of the following is an example of sanitization?

A) A public toilet is treated with disinfectants.
B) A nurse prepares an injection site with an alcohol swab.
C) An autoclave is used to prepare nutrient agar.
D) Heat is used to kill potential pathogens in apple juice.
E) A surgeon washes her hands before surgery.

Question 13

Which of the following statements is TRUE of disinfectants?

A) They are used for sterilization.
B) They are only effective for short periods of time (seconds to minutes).
C) They are effective in destroying endospores.
D) They are used on living tissue.
E) They are used on inanimate surfaces.

Question 14

Air can be disinfected using

A) HEPA filters.
B) ultraviolet light.
C) ethylene oxide.
D) both HEPA filters and ultraviolet light.
E) both ethylene oxide and ultraviolet light.

Question 15

Which of the following describes flash pasteurization?

A) heating at 72°C for 15 seconds
B) heating at 134°C for one second
C) passing liquid through steam at 140°C
D) heating at 72°C for 15 minutes
E) heating at 63°C for 30 minutes

Question 16

Which of the following is used for microbial control in fresh fruits and vegetables?

A) X-rays
B) ultraviolet light
C) electron beams
D) gamma rays
E) microwaves

Question 17

Physical removal of microbes without killing them is

A) sanitization.
B) germicidal.
C) degerming.
D) germistatic.
E) antisepsis.

Question 18

Boiling water for 10 minutes is effective in ridding it of

A) enveloped viruses.
B) bacterial endospores.
C) protozoan cysts.
D) actively growing bacteria.
E) both growing bacteria and enveloped viruses.

Question 19

Silvadene, a topical treatment for burns, contains 1% silver. What category of chemical control agent is in Silvadene?

A) heavy metals
B) aldehydes
C) oxidizing agents
D) halogens
E) surfactants

Question 20

Which of the following is bacteriostatic?

A) autoclaving
B) flash pasteurization
C) freezing below 0°C
D) heating in an oven at 171°C for an hour
E) filtration

Question 21

Alcohols are used for

A) sterilization.
B) antisepsis.
C) disinfection.
D) both sterilization and disinfection.
E) both antisepsis and disinfection.

Question 22

Which of the following procedures is currently the standard test used in the United States for evaluating the efficiency of antiseptics and disinfectants?

A) phenol coefficient
B) in-use test
C) microbial death rate
D) use-dilution test
E) thermal death point

Question 23

Honey can be stored at room temperature for long periods of time because it

A) is highly acidic.
B) is hypertonic.
C) is a natural surfactant.
D) contains oxidizing agents.
E) contains lysozyme.

Question 24

The heavy metal compound is used as a preservative in some vaccines.

A) zinc oxide
B) copper sulfate
C) silver nitrate
D) hexachlorophene
E) thimerosal

Question 25

Hydrogen peroxide is NOT an effective antiseptic because

A) it evaporates too quickly.
B) exposure to light rapidly degrades it.
C) the catalase present in skin cells degrades it.
D) it is only effective on a small number of fungi.
E) it is mostly water.

Question 26

The chemical agents known as ʺquatsʺ are used for

A) quantifying antimicrobial activity.
B) disinfection.
C) antisepsis.
D) sterilization.
E) neither antisepsis nor disinfection.

Question 27

Which of the following is a sterilizing agent?

A) ozone
B) peracetic acid
C) hydrogen peroxide
D) dish soap
E) ozone and hydrogen peroxide

Question 28

Formaldehyde must be handled with greater care than gluteraldehyde because it is

A) far more reactive.
B) a carcinogenic gas.
C) an odorless gas.
D) carcinogenic.
E) a gas.

Question 29

The use of lysozyme during the preparation of cheeses and wines is effective in reducing the numbers of

A) viruses.
B) bacteria.
C) prions.
D) fungi.
E) all microbes.

Question 30

The process of incineration is used for

A) disinfection.
B) sterilization.
C) sanitization.
D) degerming.
E) both disinfection and sanitization.

Question 31

Which of the following would be used to sterilize a mattress?

A) ethylene oxide
B) formaldehyde
C) radiation
D) heavy metals
E) autoclaving

Question 32

Desiccation is primarily effective against

A) enveloped viruses.
B) vegetative bacteria.
C) nonenveloped viruses.
D) vegetative fungi.
E) bacterial endospores.

Question 33

The endospores of which of the following microbes are used to measure the effectiveness of autoclave sterilization?

A) Neisseria gonorrhoeae
B) Mycobacterium bovis
C) Bacillus stearothermophilus
D) Pseudomonas aeruginosa
E) Clostridium botulinum

Question 34

What factors need to be considered when choosing a method of microbial control?

A) the site and the environment to be treated
B) the environment of the site or material to be treated
C) the susceptibility of the microbes which must be removed
D) the site or material to be treated
E) the site and environment to be treated, and the susceptibility of the microbes

Question 35

Disinfecting agents naturally produced by microorganisms are

A) quats.
B) halogens.
C) triclosans.
D) aldehydes.
E) antimicrobials.

Question 36

Which of the following antimicrobial agents is the most toxic to humans?

A) chloramines
B) quats
C) 70% alcohol
D) iodophors
E) ethylene oxide

Question 37

The phenolic is present in many consumer products labeled ʺantibacterial.ʺ

A) hydrogen peroxide
B) calcium hypochlorite
C) ethylene oxide
D) formaldehyde
E) triclosan

Question 38

A researcher has discovered a new metabolic product of a fungus that may have antimicrobial properties. Which method would be best for preparing the material for tests of its effect on bacteria?

A) filtration
B) dilution with alcohol
C) lyophilization
D) ultraviolet irradiation
E) autoclaving

Question 39

Which statement about quaternary ammonium compounds is CORRECT?

A) They are a type of halogen.
B) They inhibit enzyme function.
C) They function by cross-linking proteins.
D) They are carcinogenic.
E) They are not effective against Pseudomonas aeruginosa.

Question 40

Disinfectants that damage membranes include

A) iodine.
B) alcohols.
C) hydrogen peroxide.
D) phenolics.
E) both alcohols and phenolics.

Question 41

Gamma irradiation is a process for

A) degerming.
B) antisepsis.
C) disinfection.
D) sterilization.
E) both antisepsis and disinfection.

Question 42

Alcohols at 70% can effectively inactivate (all/enveloped/nonenveloped) viruses.

Question 43

The pH conditions under which a chemical disinfectant is used do not alter its efficacy.

Question 44

Nothing short of incineration is effective in destroying prions.

Question 45

The process of freeze-drying microbes to preserve them is (lyophilization/dessication).)

Question 46

By themselves, soaps have only degerming activity, not antimicrobial activity.

Question 47

Why is Bacillus stearothermophilus useful as an indicator of sterility?

A) It is a very common contaminant.
B) Only incineration will destroy it.
C) It has a cell wall containing a waxy compound which protects it from drying and aqueous disinfectants.
D) It forms cysts which resist a wide range of disinfectant methods.
E) It forms endospores, among the most hardy of microbial contaminants.

Question 48

Removal of microbes from the skin is antisepsis.

Question 49

Slow freezing is more damaging to microbial cells than quick freezing.)

Question 50

The compound ethylene oxide is used in

A) degerming.
B) disinfection.
C) antisepsis.
D) sterilization.
E) sanitization.

Question 51

Natural antiseptics such as pine or clove oil are examples of antimicrobial compounds called (alcohols/phenolics/detergents).

Question 52

The decimal reduction time is the time required to kill all the microbes in a given sample.

Question 53

Refrigeration is an effective germicidal method.

Question 54

The lowest temperature that kills all cells in a broth in 10 minutes is known as the (microbial/thermal) death point.

Question 55

Disinfectants known as (alcohols/oxidizers/aldehydes) have the chemical group -CHO, which reacts with and damages both proteins and nucleic acids.

Question 56

No chemical or antimicrobial agents inactivate prions.

Question 57

may be achieved using chlorine dioxide.

A) Degerming
B) Disinfection
C) Sterilization
D) Antisepsis
E) Both antisepsis and degerming

Question 58

Glutaraldehyde acts on microbes by

A) disrupting cytoplasmic membranes.
B) cross-linking thymidines in DNA.
C) denaturing proteins.
D) forming chemical cross links in DNA and proteins.
E) inhibiting enzyme activity.

Question 59

Some viruses are inactivated by the same chemical or physical agents that damage cytoplasmic membranes.

Question 60

The phenol coefficient is one of the most widely used measurements of an antimicrobial agentʹs effectiveness.

Question 61

Design an experiment to compare the effectiveness of a physical and a chemical method of disinfection.

Question 62

The (endospores/cysts/prions) are the infectious agents most resistant to antimicrobial agents or processes.

Question 63

Microbial growth in jellies is inhibited by the (acidic/hypotonic/hypertonic) condition of the food.

Question 64

The deadliest, most contagious microbes are studied under conditions of (BSL-4/BSL-3/BSL-2/BSL-1) containment.

Question 65

Some scientists are pursuing the use of bacteriophage as an alternative to chemical disinfectants. Discuss the advantages and disadvantages of such an approach.

Question 66

The amount of time needed to sterilize materials using moist heat is (more/less) than the time needed to sterilize using dry heat.

Question 67

The antimicrobial chemical in Figure 9-1 is a(n) (phenolic/surfactant/enzyme) compound found in many consumer products.

Question 68

The effectiveness of sterilization procedures is evaluated using (prions/cysts/endospores) because of their resilience.

Question 69

The process of heating milk or fruit juice to levels that kill any pathogenic microbes present is known as (pasteurization/sanitization/lyophilization).

Question 70

A student is shopping for antibacterial hand cleansers and is trying to decide which one to buy. One is a
ʺwaterlessʺ hand gel containing 70% isopropanol, the second is an ʺantibacterialʺ hand soap containing triclosan (a phenolic), and the third is a wipe that lists benzethonium chloride (a synthetic quaternary ammonium salt) as the active ingredient. Compare and contrast these cleansers in terms of the action of the antimicrobial ingredient and the level of disinfection (degerming, germistatic, germicidal).

Question 71

Heavy metal and oxidizing agent disinfectants damage (proteins/DNA/membranes), interfering with microbial metabolism.

Question 72

Elements such as iodine, chlorine, and bromine are examples of (oxidizers/halogens/metals) and are the basis for many effective antimicrobial agents.

Question 73

What is the in-use test, and why is it more useful than other methods of evaluating disinfectants?

Question 74

Compare and contrast the nine major types of antimicrobial chemicals in terms of their effective on microbes.

Question 75

Ultraviolet light penetrates (more/less) effectively than gamma rays.