Controlling Microbial Growth in the Environment

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Chapter 9 Microbiology, Bauman

Antimicrobial agents that disrupt the cell membrane will also damage ______.
a) cellular DNA
b) cellular enzymes
c) the viral envelope
d) the cell wall

The viral envelope.

Which of the following is an incorrect pairing?
a) iodophor; disinfection of drinking water
b) chloramine; disinfection of municipal water supplies
c) chloride dioxide; disinfection of building air
d) bromine; hot tub disinfectant

Iodophor; disinfection of drinking water

The thermal death point is the time required to completely sterilize a particular volume of liquid at a set temperature.
True or False?

False. The thermal death point is the lowest temperature that kills all cells in a broth in 10 minutes.

Which of the following organisms would still be present in a solution sterilized by filtration with a filter with 0.45 um pores?
a) bacteria
b) viruses
c) protozoa
d) yeasts

Viruses

Which of the following compounds is no longer used to preserve vaccines?
a) hexachlorophene
b) thimerosal
c) calcium hypochlorite
d) silver nitrate

Thimerosol

All of the following antimicrobial agents function by chemically crosslinking and inactivating proteins and nucleic acids EXCEPT:
a) ethylene oxide
b) beta-propiolactone
c) glutaraldehyde
d) peracetic acid

Peracetic acid

Which of the following items would typically be sanitized?
a) surgical instruments
b) restaurant utensils
c) milk
d) skin

restaurant utensils

Some species of bacteria can actually live within quat type disinfectants. T or f?

True

Which of the following statements concerning microbial death is CORRECT?
a) It is the same for all microbes under all conditions
b) It can be plotted on a semilogarithmic graph
c) It is a loss of reproductive ability that lasts for 12 to 24 hours
d) It begins rapidly, then gradually slows down until it stops

It can be plotted on a semilogarithmic graph

Which of the following tests gives the most accurate picture of the activity of a disinfectant in a particular environment or application?
a) the in-use test
b) the use-dilution test
c) the Kelsey-Sykes capacity test
d) the phenol coefficient

The in-use test

Which of the following biosafety levels would be most likely used for work with the bacteria that cause anthrax or tuberculosis?
a) BSL-1
b) BSL-2
c) BSL-3
d) BSL-4

BSL-3

Which of the following microbial control procedures creates pyrimidine dimers in DNA?
a) ionizing radiation
b) autoclaving
c) heavy metals
d) nonionizing radiation

Nonionizing radiation

Medical instruments should be sterilized first and then cleaned after sterilization. T or F?

False.

A medical assistant needs to disinfect a medical instrument that comes in contact with mucous membranes but is noninvasive. Which category is best?
a) high-level germicide
b) intermediate-level germicide
c) intermediate-level fungicide
d) low-level germicide

Intermediate-level germicide

Which of the following categories of chemical agents is NOT correctly matched with an example from that category?
a) oxidizing agent; peracetic acid
b) quat; Cepacol mouthwash
c) gaseous agent; hydrogen peroxide
d) halogen sodium hypochlorite

Gaseous agent; hydrogen peroxide

The major difference between disinfection and sanitization is the setting in which the activity takes place. T or F?

True

Sodium hypochlorite is an example of a halogen-containing antimicrobial agent. T or F?

True

The infectious agent forms that are MOST RESISTANT to antimicrobial control are bacterial endospores. T or F?

False.

The antimicrobial agent approved in 2006 for the removal of prions from medical instruments belong to which of the following groups?
a) gaseous agents
b) oxidizing agents
c) halogens
d) antimicrobial enzymes

Antimicrobial enzymes

All of the following microbes are killed by pasteurization EXCEPT:
a) Brucella melitensis
b) E. coli
c) Bacillus stearothermophilus
d) Mycobacterium bovis

Bacillus stearothermophilus

A nurse prepares an area of skin for injection by scrubbing it with an alcohol swab; this process is called:
a) sterilization
b) degerming
c) disinfection
d) sanitization

degerming

Which of the following terms includes the destruction of bacterial endospores?
a) pasteurization
b) antisepsis
c) sanitization
d) sterilization

sterilization

A membrane filter with a pore size of 1.2 micrometers would trap all of the following EXCEPT:
a) bacteria
b) multicellular fungi
c) yeasts
d) protozoa

bacteria

All of the following would contribute to the increased efficiency of an antimicrobial agent EXCEPT:
a) higher concentrations of the agent
b) higher temperatures
c) longer exposure to cells
d) higher pH

higher pH

All of the following statements concerning autoclaving are true EXCEPT:
a) under 15 PSI of pressure, water boils at 121 C
b) Large volumes or solid substances require longer autoclaving times
c) Any material that needs to be sterilized should be autoclaved
d) In order for an item to be sterilized in an autoclave, steam must contact all its surfaces

Any material that needs to be sterilized should be autoclaved

A particular machine passes milk through steam at a temperature of 140C for one second and then cools it rapidly. This is an example of:
a) ultrahigh-temperature sterilization
b) autoclaving
c) ultrahigh-temperature pasteurization
d) pasteurization

Ultrahigh-temperature sterilization

All of the following microbial control methods are bacteriostatic EXCEPT:
a) desiccation
b) ionizing radiation
c) refrigeration
d) lyophilization

ionizing radiation

All of the following are examples of ionizing radiation EXCEPT:
a) gamma rays
b) ultraviolet light
c) electron beams
d) x rays

Ultraviolet light

Which of the following antimicrobial agents can disrupt the cell membrane?
a) quaternary ammonium compounds
b) halogens
c) heavy metals
d) aldehydes

Quaternary ammonium compounds

Which of the following is NOT a gaseous antimicrobial agent?
a) glutaraldehyde
b) beta-propiolactone
c) propylene oxide
d) ethylene oxide

Glutaraldehyde

The decimal reduction time for endospores of Clostridium botulinum is 0.204 minutes at 121 C. How long should it take to reduce a population of 10^15 endospores to 1 endospore?
a) 1.3 minutes
b) 2.0 minutes
c) 2.5 minutes
d) 3.1 minutes

3.1 minutes (0.204 x 15 = 3.06, rounded up to 3.1 minutes)

These organisms are heat-tolerant microbes that can survive pasteurization.

Thermoduric

This is an alcohol solution of an antimicrobial chemical.

Tincture

This is a phenolic compound that has been incorporated into such consumer products such as garbage bags and diapers.

Triclosan

Formaldehyde that has been diluted in water to create a solution of 37% formaldehyde is called this.

Formalin

This is a reactive form of oxygen produced by subjecting molecular oxygen to an electrical discharge.

Ozone

These germicides are used to disinfect items that will come into contact with only the skin of patients.

Low-Level

These are infectious proteins that cannot be eliminated by standard sterilizing techniques.

Prions

These are agents that kill fungal cells.

Fungicides

Air can be filtered and disinfected by the use of special filters with the acronym what?

HEPA

Soaps and detergents are two common examples of what?

Surfactants

T or F: Antimicrobics are used for treatment of infectious disease, not for the control of microbes in a particular environment.

True
(Although some antimicrobics are used in antimicrobial control outside the body, most are not.)

T or F: Control agents that contain heavy metals work by binding to cysteine molecules in microbial proteins.

True
(Sulfur is a binding target of heavy metals in microbial proteins.)

T or F: Pure alcohol is the most effective form of alcohol as an antimicrobial agent.

False
(The denaturation of proteins caused by alcohol requires the presence of water, so the most effective antimicrobial forms of alcohol are 70-90% solutions)

T or F: Sodium hypochlorite is an example of a halogen-containing antimicrobial agent.

True
(Sodium hypochlorite is the active ingredient in chlorine bleach.)

T or F: A surfactant makes a solvent such as water more effective at dissolving solute molecules.

True
(Surfactants work by decreasing the attraction between water molecules.)

T or F: Protozoan cysts are more resistant to antimicrobial control agents than are bacteria.

True
(Protozoan cysts are among the most resistant forms of microbes.)

T or F: Water that is boiling rapidly is a better disinfectant than water kept at a slow boil.

False
(No matter how much heat is applied to boiling water, it remains at the same temperature and disinfects at the same rate.)

T or F: Autoclaving is the only form of moist heat that is able to sterilize.

False
(Ultrahigh-temperature sterilization can also be used to sterilize materials such as dairy creamer.)

T or F: Sterilization using an oven requires either higher temperatures or longer times than autoclaving to achieve the same result.

True
(Materials can be sterilized in an oven after one hour at a temperature of 171 C.)

T or F: Because microwaves are a form of nonionizing radiation, they are a practical antimicrobial agent.

False
(Microwaves do not contain sufficient energy to be a practical antimicrobial agent.)

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