Chapter 8 - Control of Microorganisms in the Environment

Which of the following inhibits bacterial growth but does not kill bacteria? A. Lysozyme B. Bactericidal agent C. Bacteriostatic agent D. Antiseptic agent

Bacteriostatic agent

Which of the following is a Gram-negative bacterium that acts as a predator on other Gram-negative bacteria, and might be used to control populations of Gram-negative human pathogens in locations such as poultry farms? A. E. coli B. Salmonella enteritidis C. Bdellovibrio D. Vibrio choerae

Bdellovibrio

Which of the following would be most effective and practical for routine home disinfection of a kitchen sponge between uses? A. 70% Isopropyl alcohol B. Iodophor C. Chlorine bleach D. Hydrogen peroxide

Chlorine bleach

Disinfectants are generally regulated by the A. Food and Drug Administration. B. Environmental Protection Agency. C. The National Institutes of Health. D. Centers for Disease Control and Prevention.

Environmental Protection Agency.

Which of the following is (are) a sterilizing gas(es) that can be used on heat-sensitive materials? A. Ethylene oxide B. Glutaraldehyde C. Chlorine gas D. Isopropanol

Ethylene oxide

Which of these is an agent that is used to sterilize the plastic tubing of heart-lung machines? A. Phenol B. Mercaptoethanol C. Ethylene oxide D. 70% ethanol

Ethylene oxide

Alcohols are widely used as antiseptics and disinfectants because they are effective against endospores as well as vegetative cells. (T/F)

False

All germicides are capable of killing all pathogenic organisms and endospores. (T/F)

False

Bacteriophage therapy was developed after antibiotics were first discovered and used for treating bacterial infections. (T/F)

False

Because filtration removes rather than destroys microorganisms, it does not truly sterilize the materials passing through the filter. (T/F)

False

Dry heat methods usually require lower temperatures and shorter exposure times than moist heat methods to achieve the same degree of killing because of the drying effects of this form of heat. (T/F)

False

If one left a "pasteurized" flask of broth for a long time at room temperature, it would stay sterile forever, at least in principle. (T/F)

False

Larger populations generally are killed as rapidly as smaller populations. (T/F)

False

Which kind of sterilization procedure takes advantage of the size of microorganisms? A. Autoclaving B. Open flame C. Use of chemicals D. Filtration

Filtration

Antiseptics are generally regulated by the A. Food and Drug Administration. B. Environmental Protection Agency. C. The National Institutes of Health. D. Centers for Disease Control and Prevention.

Food and Drug Administration.

Several new materials have been developed for use in the microbiology lab. These materials must be sterilized before use, but cannot withstand a temperature over 60oC and can't be exposed to water. Which method of sterilization would be applicable? A. Steam autoclave B. Oven-dry heat C. UV radiation D. Ionizing radiation

Ionizing radiation

Microorganisms show differential sensitivity to antimicrobial agents. (T/F)

True

The rate of killing by an antimicrobial agent may slow when the microbial population has been greatly reduced because the remaining population may have a high proportion of resistant organisms. (T/F)

True

Ultraviolet radiation is an effective means of sterilizing surfaces. (T/F)

True

Moist heat sterilization at 100C kills all of the following EXCEPT A. bacterial endospores. B. fungal spores. C. viruses. D. bacterial endospores and fungal spores.

bacterial endospores.

An agent that kills bacteria is referred to as __________.

bactericidal

Bacterial pathogens may be controlled by ___________________, which are viruses that specifically infect and lyse the bacterial host.

bacteriophage or phage

An agent that prevents the growth of bacteria without causing irreversible damage to the bacteria is referred to as __________.

bacteriostatic

An agent that specifically kills fungi but not other kinds of microorganisms is also known as a A. fungistatic agent. B. mycostatic agent. C. fungicidal agent. D. germicidal agent.

fungicidal agent.

Which of the following influence(s) the efficiency of an antimicrobial agent? A. concentration of the agent B. duration of exposure C. temperature D. All of the choices are correct.

All of the choices are correct.

Which of the following is a function of pasteurization? A. Killing pathogenic microorganisms B. Reducing the total microbial population C. Increasing the shelf life of the product D. All of the choices are correct.

All of the choices are correct.

Which of the following is/are advantages of using bacteriophage to treat human bacterial infections? A. Bacteriophage can kill the bacteria. B. Bacteriophage will not cause disease or harm humans. C. Bacteriophage are very specific for the target bacteria and won't affect normal microbiota. D. All of the choices are correct.

All of the choices are correct.

Which of the following is MOST effective against resistant endospores? A. Autoclaving B. Boiling C. Pasteurization D. All of these are equally effective against resistant endospores.

Autoclaving

The type of filter used in a laminar flow biological safety cabinet is called a(n) __________ filter.

HEPA (high efficiency particulate air)

Heavy metals are effective antimicrobial agents but are not widely used because of their high toxicity to humans. (T/F)

True

Which of the following would be most effective and practical for routine home disinfection of a toothbrush between uses? A. 70% Isopropyl alcohol B. Glutaraldehyde C. Bleach D. Hydrogen peroxide

Hydrogen peroxide

Which of the following is true about membrane filters? A. It can be used only to remove organisms from liquids. B. It does not truly sterilize because it removes rather than kills microorganisms. C. It can be used only to remove organisms from liquids and it does not truly sterilize because it removes rather than kills microorganisms. D. It can't be depended on to remove all viruses from liquids.

It can't be depended on to remove all viruses from liquids.

Which of the following would be most appropriate for removal of bacteria and viruses from a liquid? A. HEPA filter B. N95 filter C. Membrane filter (0.01µm) D. Depth filter (diatomaceous earth)

Membrane filter (0.01µm)

Which of the following is not a method of heat sterilization? A. Autoclaving B. Incineration C. Pasteurization D. Heating in a dry air oven

Pasteurization

Heavy metals may inactivate proteins by reacting with their sulfhydryl groups. (T/F)

True

Which of the following represents the best definition for microbial death? A. The organism will not grow on minimal medium. B. The organism will not grow on a medium that normally supports its growth. C. The organism no longer retains its original shape and structures. D. None of these adequately describe microbial death.

The organism will not grow on a medium that normally supports its growth.

A biological safety cabinet filters out more microorganisms than an N95 mask. (T/F)

True

Betapropiolactone is not as useful as ethylene oxide as a sterilizing agent because it does not penetrate materials as readily as ethylene oxide. (T/F)

True

Fecal transplants have been successfully used to treat Clostridium difficile colitis by reintroducing healthy fecal microbiota that outcompete the C. difficile. (T/F)

True

Portable UV room sterilizing units are being used to reduce endospores of Clostridum difficile in patient hospital rooms after patients have vacated the room. Which of the statements best describes this application? A. UV radiation will not destroy C. difficile endospores. B. UV radiation will destroy C. difficile endospores assuming it is applied for a long enough period and directly contacts all surfaces. C. UV radiation will destroy C. difficile endospores and penetrates well to all locations within the room. D. UV radiation will destroy C. difficile endospores and has residual sporicidal effects that will persist after the unit has been removed from the patient's room.

UV radiation will destroy C. difficile endospores assuming it is applied for a long enough period and directly contacts all surfaces.

Which of the following lacks sufficient penetrating power for bulk sterilization? A. Ultraviolet (UV) radiation at 260 nm B. X rays C. Gamma radiation D. Alpha and beta particles

Ultraviolet (UV) radiation at 260 nm

Which will require a longer time to kill? A. a larger population of microorganisms B. a smaller population of microorganisms C. Killing will be equally as rapid in a large or a small microbial population. D. There is no way to predict which will require a longer kill time.

a larger population of microorganisms

The prevention of infection caused by microorganisms is called A. disinfection. B. antisepsis. C. sterilization. D. sanitization.

antisepsis.

The disinfectant of choice for municipal water supplies is __________. A. fluorine B. chlorine C. either fluorine or chlorine D. ultraviolet light

chlorine

Although heavy metals are no longer widely used as germicides, __________ is an effective algicide in lakes and swimming pools. A. lead acetate B. copper sulfate C. silver nitrate D. mercuric chloride

copper sulfate

The time required to kill 90% of the microorganisms or spores in a sample at a specified temperature is the A. thermal death time (TDT). B. thermal death point (TDP). C. decimal reduction time (D value). D. z value.

decimal reduction time (D value).

Moist heat sterilizes by A. causing the formation of thymine dimers. B. denaturing proteins. C. causing production of singlet oxygen. D. All of the choices are correct.

denaturing proteins.

Amphipathic organic molecules that serve as disinfectants by disrupting membranes and denaturing proteins are called A. sterilants. B. oxidants. C. detergents. D. soaps.

detergents.

The substantial reduction of the total population of microorganisms on inanimate objects and the destruction of potential pathogens is called A. disinfection. B. antisepsis. C. sterilization. D. sanitization.

disinfection.

The two most important alcohol germicides are __________ and __________. A. ethanol; methanol B. ethanol; isopropanol C. methanol; butanol D. methanol; isopropanol

ethanol; isopropanol

Iodine can be complexed with an organic carrier to form water-soluble, stable complexes called __________, which release iodine slowly and eliminate skin burns and irritation associated with iodine use. A. iodides B. tinctures C. iodophors D. iodochromes

iodophors

Gamma radiation A. is a type of nonionizing radiation. B. has poor penetrating power. C. is used to sterilize some food products. D. has a longer wavelength than UV radiation.

is used to sterilize some food products.

Pasteurization is used to A. kill any pathogens present. B. retard spoilage. C. sterilize beverages. D. kill any pathogens present and retard spoilage.

kill any pathogens present and retard spoilage.

Sterilization involves __________ all viable microorganisms. A. killing B. removing C. killing OR removing D. metabolically inactivating

killing OR removing

When antiseptics and disinfectants are compared, antiseptics are generally A. less toxic. B. more toxic. C. equally as toxic. D. unpredictable in toxicity.

less toxic

The disinfectant action of phenol and phenolic derivatives mainly is due to A. its inherent detergent action. B. membrane damage and protein denaturation. C. oxidation of disulfide bonds in proteins. D. extraction of lipids from membranes. E. damage to nucleic acids and proteins caused by free radicals.

membrane damage and protein denaturation.

The higher the phenol coefficient value, the _______ effective the disinfectant under the test conditions.

more

The disinfectant screening method that is known as the ________ _________ test, which is used to measure the potency of a disinfectant.

phenol coefficient

The disinfecting properties of Lysol, a common household disinfectant, depend upon the presence of __________.

phenolics

Which of the following environmental factors generally do(es) not have an impact on the efficiency of an antimicrobial agent? A. pH B. presence or absence of a biofilm C. concentration of organic matter D. refractive index

refractive index

Joseph Lister A. pioneered the use of gamma rays for sterilizing food. B. demonstrated that microorganisms are carried on dust particles in the air. C. revolutionized surgery by introducing phenol as a disinfectant. D. designed and built the first autoclave.

revolutionized surgery by introducing phenol as a disinfectant.

The reduction of the microbial population to levels that are considered safe by public health standards is called A. disinfection. B. antisepsis. C. sterilization. D. sanitization.

sanitization

When comparing dry heat and moist heat sterilization, dry heat is A. faster. B. slower. C. equally as fast. D. sometimes faster but sometimes slower.

slower.

A(n) __________ is a chemical that can be used to sterilize materials. A. oxidant B. disinfectant C. antiseptic D. sterilant

sterilant

The destruction or removal of all viable organisms is called A. disinfection. B. antisepsis. C. sterilization. D. sanitization.

sterilization

The use of bacteriophage to treat human infections is referred to as phage ___________.

therapy

The first product to be commercially treated by pasteurization was A. milk B. wine C. beer D. cheese

wine