Deck 11: Physical and Chemical Agents for Microbial Control

Question 1

Endospores can be killed by

A)dry heat at 170°C for 2 hours.
B)incineration.
C)glutaldehyde for 8 or more hours.
D)ethylene oxide for 3 or more hours.
E)All of these choices are correct.

Answer 1

E

Question 2

Microbiological contaminants are best described as

A)unwanted microbes present on or in a substance.
B)any and all microbes present on or in a substance.
C)pathogenic microbes present on or in a substance.
D)vegetative microbes present on or in a substance.

Answer 2

A

Question 3

The process of using a cleansing technique to mechanically remove and reduce microorganisms and debris to safe levels is

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

Answer 3

D

Question 4

HEPA filters are used to remove microbes from

A)air.
B)liquids.
C)human tissues.
D)medical instruments.
E)All of these choices are correct.

Question 5

Dry heat

A)is less efficient than moist heat.
B)cannot sterilize.
C)includes tyndallization.
D)is used in devices called autoclaves.
E)will sterilize at 121°C for 15 minutes.

Question 6

Scrubbing or immersing the skin in chemicals to reduce the numbers of microbes on the skin is

A)disinfection.
B)sterilization.
C)sanitization.
D)degermation.

Question 7

Which of the following types of control agents would be most likely to achieve sterility?

A)virucide
B)bactericide
C)germicide
D)sporicide
E)fungicide

Question 8

Which of the following microbial forms have the highest resistance to physical and chemical controls?

A)naked viruses
B)protozoan cysts
C)fungal spores
D)bacterial endospores
E)yeast

Question 9

Electrons are ejected from atoms in cells when organisms are exposed to

A)dessication.
B)ultraviolet light.
C)ethyl alcohol.
D)hydrogen peroxide.
E)gamma rays and X-rays.

Question 10

Sterilization is achieved by

A)flash pasteurization.
B)hot water.
C)boiling water.
D)steam autoclave.
E)All of these choices are correct.

Question 11

All of the following are major categories of microbial control methods except

A)physical agents.
B)chemical agents.
C)mechanical removal methods.
D)genetic methods.

Question 12

Disinfection of beverages, such as apple juice, milk, and wine, is optimally achieved by

A)pasteurization.
B)chlorination.
C)moist heat autoclave.
D)filtration.
E)boiling water.

Question 13

The use of chemical agents directly on exposed body surfaces to destroy or inhibit vegetative pathogens is

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

Question 14

The minimum sterilizing conditions in a steam autoclave are

A)121°C at 15 psi for 15 minutes.
B)63°C for 30 minutes.
C)160°C for 2 hours.
D)71.6°C for 15 seconds.
E)100°C for 30 minutes.

Question 15

The use of a physical or chemical process to destroy vegetative pathogens on inanimate objects is

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

Question 16

The process that destroys or removes all microorganisms and microbial forms including bacterial endospores is

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

Question 17

Which of the following items are typically irradiated in order to kill microbes?

A)ground beef and other meat and poultry
B)human tissues such as heart valves and skin
C)operating room air
D)surgical gloves
E)All of these choices are correct.

Question 18

Physical agents for controlling microbial growth include all of the following, except

A)ultraviolet radiation.
B)boiling water.
C)HEPA filters.
D)pasteurization.
E)hydrogen peroxide.

Question 19

The shortest time required to kill all the microbes in a sample at a specified temperature is called the

A)thermal death point (TDP).
B)thermal death time (TDT).
C)sporicidal time.
D)death phase point.

Question 20

Which is correct regarding the rate of microbial death?

A)Cells die at increasingly greater rates.
B)Only older cells die in a culture.
C)Cells in a culture die at a constant rate.
D)Upon contact with the control agent, all cells die at one time.
E)Cells become metabolically inactive but are never killed.

Question 21

The chemical agent(s) that produces highly reactive hydroxyl-free radicals and also decomposes to O₂ gas is/ are

A)Cidex.
B)cationic detergents.
C)hydrogen peroxide.
D)chlorhexidine.
E)iodophors.

Question 22

All of the following pertain to hypochlorites, except

A)they release hypochlorous acid in solution.
B)they cause denaturation of enzymes.
C)they are found in iodophors.
D)they are used to disinfect dairy, restaurant, and medical equipment.
E)they are found in common household bleach.

Question 23

All of the following are correct about iodophors, except

A)they are complexes of iodine and a neutral polymer.
B)this formulation allows a quick release of free iodine.
C)this formulation increases its penetration.
D)it is less prone to staining or irritating tissue.
E)a common iodophor is Betadine.

Question 24

The sterilizing gas used in a special chamber is

A)ethylene oxide.
B)iodophor.
C)glutaraldehyde.
D)formaldehyde.
E)chlorine dioxide.

Question 25

Which of the following chemicals is a disinfectant for soft contact lenses?

A)hydrogen peroxide
B)alcohol
C)hexachlorophene
D)glutaraldehyde
E)hypochorites

Question 26

The compound that is an organic base containing chlorine and two phenolic rings and is used increasingly for hand scrubbing, neonatal washes, wound degerming, and prepping surgical skin sites is

A)carbolic acid.
B)chlorhexidine.
C)triclosan.
D)formalin.
E)quarternary ammonium compounds.

Question 27

All of the following are correct about food irradiation, except

A)food is not made radioactive by the process.
B)the World Health Organization does not endorse this process.
C)it is approved in the U.S.for beef, chicken, and pork.
D)it can lead to a longer shelf life for the irradiated food.
E)no irradiated food can be sold without clear labeling.

Question 28

All of the following are phenols or phenolics, except

A)lysol.
B)hexachlorophene.
C)triclosan.
D)cresols.
E)chloramines.

Question 29

Which of the following does not contain a heavy metal?

A)tincture of iodine
B)merthiolate
C)silver nitrate solutions
D)zinc
E)mercurochrome

Question 30

The easiest microbial forms to kill or inhibit are

A)naked viruses.
B)vegetative bacteria and fungi.
C)endospores.
D)protozoan cysts.
E)Mycobacterium and Staphylococcus.

Question 31

Which is mismatched?

A)sodium hypochlorite-chlorine
B)iodophor-iodine
C)benzalkoniumchloride-quaternary ammonium compound
D)chlorhexidine-alcohol
E)formalin-formaldehyde

Question 32

All of the following are benefits of food irradiation, except

A)it can kill bacterial pathogens on the food.
B)it can kill insects on the food.
C)it can inhibit the sprouting of white potatoes.
D)it can reduce the number of food-borne deaths each year.
E)it makes the food less nutritious.

Question 33

Which of the following is not used as an antiseptic?

A)iodophor
B)chlorhexidine
C)3% hydrogen peroxide
D)ethyl alcohol
E)aqueous glutaraldehyde

Question 34

Which of the following is officially accepted as a sterilant and high-level disinfectant?

A)benzalkonium chloride
B)silver nitrate
C)glutaraldehyde
D)triclosan
E)cresol

Question 35

All the following are correct about detergents, except

A)they are polar molecules that act as surfactants.
B)the most effective ones are positively charged.
C)in low concentrations they are bacteriostatic.
D)they are ineffective against the tuberculosis bacteria.
E)they are active in the presence of organic matter.

Question 36

Iodophors include

A)chloramines.
B)povidone iodine.
C)tincture of iodine.
D)alcohols.
E)chlorhexidine.

Question 37

Ethylene oxide is

A)sporicidal.
B)only effective with high heat.
C)the active agent in household bleach.
D)used as an antiseptic against anaerobes.
E)a halogen.

Question 38

Alcohols

A)denature proteins when in a 50-95% solution.
B)are used to disinfect items by soaking.
C)are skin degerming agents.
D)at 50% or higher concentrations dissolve cell membrane lipids.
E)All of these choices are correct.

Question 39

Which of the following is being used to replace hypochlorites in treating water because of the possibility of cancer-causing substances being produced?

A)hydrogen peroxide
B)chloramines
C)fluorine
D)quaternary ammonium compounds
E)sodium iodide

Question 40

Which control method would not be a suitable choice for killing Mycobacteria in a capped culture tube?

A)ultraviolet (germicidal) light
B)gamma rays
C)121°C at 15 psi for 15 minutes
D)160°C for 2 hours
E)All of these choices are correct.

Question 41

All of the following are correct about the autoclave, except

A)it is important not to overload the chamber.
B)it is effective for sterilizing powders, oils, and waxy substances.
C)the duration of the process depends on how full the chamber is.
D)it is the temperature that kills the microbes, not the pressure by itself.
E)sterilization is achieved when steam condenses against the objects in the chamber and raises their temperatures.

Question 42

Which of these metals have antimicrobial properties associated with them?

A)Silver
B)Gold
C)Tin
D)Aluminum
E)both silver and gold

Question 43

Bacteriostatic agents kill bacterial cells.

Question 44

Historically, which of the following was instilled into the eyes of newborn infants to prevent gonococcal infections?

A)triclosan
B)formaldehyde
C)phenol
D)silver nitrate
E)mercurochrome

Question 45

Which common hospital pathogen is able to grow abundantly in soap dishes?

A)Escherichia coli
B)Pseudomonas
C)Hemophilus influenzae
D)Mycobacteria tuberculosis
E)Salmonella

Question 46

Chlorine compounds remain stable and effective in the presence of excess organic matter.

Question 47

Which of the following types of agents targets protein conformation?

A)detergents
B)ultraviolet light
C)alcohol
D)hydrogen peroxide
E)crystal violet

Question 48

The presence of organic matter such as saliva and pus can interfere with the actions of disinfectants.

Question 49

All of the following are methods of disinfection or sterilization, except

A)gamma radiation.
B)dry oven.
C)lyophilization.
D)triclosan.
E)ethanol.

Question 50

Alcohols are more effective at inactivating enveloped viruses than naked viruses.

Question 51

Using toilet bowl cleaner and nonionizing radiation on inanimate surfaces only removes or kills vegetative bacteria.The term that best describes this action is

A)sterilization.
B)disinfection.
C)antisepsis.
D)degermation.

Question 52

Aniline dyes like crystal violet have antimicrobial activity particularly against gram-positive bacteria and some fungi.

Question 53

When a control agent targets the metabolic processes of microbial cells, active younger cells typically die more rapidly than older cells.

Question 54

Isopropyl alcohol wiped across a skin site can sterilize it.

Question 55

Filtration is an effective method to remove microbes from air and liquids.

Question 56

Chlorine dioxide and ethylene oxide are gaseous sterilants.

Question 57

Bacteriocidal agents are sterilants.

Question 58

Commercial products containing which types of chemicals are more effective at killing microorganisms?

A)bacteriostatic
B)bacteriocidal
C)carbohydrate
D)lead

Question 59

Most microbial contaminants of food are killed at freezing temperatures.

Question 60

A microorganism that is not motile and has stopped metabolizing could be considered dead.

Question 61

_____ filters are widely used to provide a flow of sterile air to hospital rooms.

Question 62

_____ is a halogen used in gaseous and liquid form for large scale disinfection of drinking water and sewage.

Question 63

Which method of microbial control destroys microorganisms by oxidation of cells?

A)steam autoclave
B)use of glutaraldehyde
C)use of UV radiation
D)incineration

Question 64

Compare and contrast antisepsis, disinfection, sanitization, and sterilization with regard to techniques used and level of microbial control achieved.

Question 65

Moist heat damages microorganisms by

A)oxidation of cellular components.
B)damaging the phospholipid bilayer.
C)damaging the cells nucleic acids.
D)denaturing and coagulating cellular proteins.

Question 66

Discuss the technique of filtration as a microbial control method, why it's utilized, and specific materials that are filtered.

Question 67

Moist heat is more efficient at killing microbes and is effective at lower temperatures or shorter exposure times than dry heat.

Question 68

_____ heat is more rapidly effective and efficient compared to _____ heat.

Question 69

Physical methods of microbial control will typically sterilize, whereas chemical methods will only disinfect.

Question 70

The thermal death time for

A)The thermal death time will be longer.
B)The thermal death time will be shorter.
C)There will be no change in thermal death time.
D)There is not enough information to make this prediction.
E)coli at 63°C was determined to be 20 minutes.Predict the affect on thermal death time if the temperature is increased to 67°C.

Question 71

Explain why boiling water is considered disinfection, not a sterilization method.List three materials commonly disinfected by boiling water.

Question 72

__________ or steam sterilization is the process by which steam is heated under pressure to sterilize objects.

Question 73

Discuss the advantages and disadvantages of irradiating food.Include examples of foods that are irradiated.

Question 74

For each item listed below, select a sterilant that you feel is the most suitable and effective for that item.Discuss why you selected each sterilant.

Question 75

_____ radiation excites atoms to a higher energy state within molecules such as DNA that then leads to the formation of pyrimidine dimers.

Question 76

Some microbial control agents are able to _____ cell proteins by breaking bonds that maintain the native state, three-dimensional configuration of the proteins.

Question 77

The thermal death point of a strain of Stapylcococcus aureus was determined to be 63°C.How would the the thermal death point of Bacillus subtilis compare?

A)The thermal death point of Bacillus subtilis would be just slightly higher than that of Staphylococcus aureus.
B)The thermal death point of Bacillus subtilis would be significantly higher than that of Staphylococcus aureus.
C)The thermal death point of Bacillus subtilis would be the same as that of Staphylococcus aureus.
D)The thermal death point of Bacillus subtilis would be lower that of Staphylococcus aureus.

Question 78

Discuss the purpose and level of control achieved by pasteurization.Compare the flash and batch methods.

Question 79

A method for sterilizing milk, called _____ temperature treatment, uses 134°C for 1 to 2 seconds.

Question 80

Vials of microorganisms that undergo the freeze-drying process called _____ will remain preserved and viable for years.