Deck 11: Principles of Sterilisation and Disinfection

Question 1

Which of the following is NOT an accepted method of sterilisation?

A)Gamma radiation.
B)Microwave radiation.
C)Steam at 121ᵒC.
D)Ethylene oxide gas.
E)Dry heat at 170ᵒC.

Answer 1

B

Question 2

The removal of microorganisms from an object using a cleaning process is called

A)antisepsis.
B)sterilisation.
C)disinfection.
D)decontamination.
E)pasteurisation.

Answer 2

D

Question 3

Which of the following chemicals can have a sterilising effect?

A)Alcohol.
B)Phenol compounds.
C)Ethylene oxide.
D)Chlorine.
E)Povidone-iodine.

Answer 3

C

Question 4

The conditions necessary to destroy endospores are

A)Boiling at 100⁰C for 15 minutes.
B)Heating to 110⁰C for 30 minutes.
C)Heating to 115⁰C for 10 minutes.
D)Heating to 121⁰C for 15 minutes.
E)Any temperature above 100⁰C for 3 minutes.

Question 5

In which of the following would a high-efficiency particulate air filter (HEPA)be used?

A)To clean the air entering operating theatres.
B)In laboratory biosafety cabinets to remove microbes from exhaust air.
C)To trap pathogens in exhaust systems from isolation units.
D)In respiratory masks.
E)All of the above.

Question 6

If a medical instrument is disinfected

A)it is safe to use for any purpose.
B)it is completely free of all microorganisms and spores.
C)it has been subjected to a process that reduces the number of microbes present.
D)it can only be used on a patient if it is in an airtight package.
E)it must have been treated with some type of chemical.

Question 7

Which of the following statements is FALSE?

A)A disinfection process removes only some bacteria and viruses.
B)An item that has been disinfected may be used to penetrate healthy skin.
C)Chemical disinfectants can be inactivated by organic material.
D)Disinfection may only remove some pathogens.
E)Washing equipment with hot water and detergent improves the effectiveness of disinfection procedures.

Question 8

A steam steriliser (autoclave)is effective because

A)water boils at a higher temperature under pressure.
B)packaging material can be dried prior to removal from the steriliser.
C)it destroys all microorganisms.
D)it destroys all viruses.
E)all of the above.

Question 9

Which of the following statements is FALSE?

A)Gamma radiation can destroy all bacteria and viruses.
B)Ionising radiation kills bacteria by disrupting the structure of their DNA.
C)Gamma radiation sterilises because it can penetrate wrapped articles.
D)Gamma radiation is useful for sterilising biological solutions for injection.
E)Microwave radiation destroys all microorganisms by denaturing their proteins.

Question 10

Which of the following methods does NOT kill endospores?

A)Steam under 1 atmosphere pressure.
B)Incineration.
C)Hot air (160⁰C)sterilisation.
D)Pasteurisation.
E)Gamma irradiation.

Question 11

In terms of processing requirements,a bedpan would be classified as

A)critical.
B)semi-critical.
C)non-critical.
D)high risk.
E)moderate risk.

Question 12

The first person to use disinfectants to reduce the rate of death from infections in surgery was

A)Joseph Lister.
B)Ignaz Semmelweis.
C)Robert Koch.
D)Edward Jenner.
E)John Snow.

Question 13

If an instrument has been sanitised

A)it has been cleaned but not necessarily disinfected or sterilised.
B)it is completely free of all microorganisms and spores.
C)the number of microbes on it has been reduced to an acceptable level.
D)it has been subjected to a chemical that disinfects but doesn't sterilise.
E)it is no longer contaminated.

Question 14

Which of the following statements is TRUE?

A)Any solution that is administered parenterally must be sterile.
B)Any equipment that penetrates the skin must be sterile before use.
C)Bedpans do not need to be sterile before use.
D)Dressings and swabs applied to damaged skin must be sterile.
E)All of the above.

Question 15

Which of the following methods is NOT a sterilising method?

A)Autoclaving at 121⁰C.
B)Treatment with ethylene oxide.
C)Irradiation with gamma rays.
D)Boiling at 100⁰C.
E)Low temperature hydrogen peroxide.

Question 16

The removal of microorganisms from an object with heat less than 100ᵒC is called

A)disinfection.
B)decontamination.
C)pasteurisation.
D)all of the above.
E)none of the above.

Question 17

Which of the following statements is TRUE?

A)Use of a disinfectant is not necessary for routine cleaning of surfaces.
B)Bedrails and over-bed tables don't need regular cleaning.
C)A dry surface is just as likely to harbour microorganisms as a wet surface.
D)Physical cleaning is not necessary if the item is to be disinfected.
E)All of the above.

Question 18

Sterilisation is a term used to describe the

A)killing of pathogenic microorganisms only.
B)destruction or removal of all viable organisms.
C)prevention of infection by microorganisms.
D)reduction of the microbial population to safe levels.
E)swabbing of the skin before giving an injection.

Question 19

A piece of medical equipment that is considered to be semi-critical

A)is one that is used in surgery.
B)is one that comes into contact with a mucous membrane.
C)should be cleaned but not disinfected before use.
D)is one that is not directly used on a patient.
E)can be re-used after careful decontamination.

Question 20

In terms of processing requirements,a urinary catheter would be classified as

A)critical.
B)semi-critical.
C)non-critical.
D)low risk.
E)moderate risk.

Question 21

A heat-sensitive,glass instrument is used on a patient known to have hepatitis B and becomes contaminated with small traces of the patient's blood.Before using it on the intact skin of another patient,which of the following would be the best way of disinfecting the instrument?

A)Cleaning with soap and water followed by disinfection with sodium hypochlorite (household bleach).
B)Cleaning with soap and water followed by disinfection with any disinfectant available.
C)Soaking the instrument in any disinfectant for several hours.
D)Cleaning with soap and water is all that is necessary.
E)None of the above because the instrument should not be used on any other patient.

Question 22

A kitchen sponge would be best decontaminated by

A)placing it in a saucepan of boiling water for a few minutes.
B)washing it in a household disinfectant.
C)putting it in the freezer for a day.
D)placing it in the microwave for a few seconds.
E)none of the above.

Question 23

Which concentration of ethyl alcohol is the most effective bactericide?

A)100%
B)90%
C)70%
D)50%
E)20%

Question 24

A bactericide is a chemical agent which

A)is effective against a range of microorganisms.
B)inhibits bacterial replication.
C)is used to sterilise the water supply.
D)kills bacteria.
E)is used to sterilise surgical instruments.

Question 25

An antiseptic

A)is a chemical substance like soap.
B)is a chemical that is mild enough to use on skin and tissue.
C)is effective against all bacteria but not viruses.
D)guarantees removal of all microbes if used appropriately.
E)should only be used on minor cuts and insect bites.

Question 26

What is most likely to happen to the bacteria in food which is placed in a refrigerator at 4⁰C?

A)They die because bacteria cannot tolerate low temperatures.
B)They continue to multiply but at a much reduced rate.
C)They produce toxins which cause gastroenteritis when the food is eaten.
D)They all form endospores in order to survive.
E)They mutate in order to survive.

Question 27

Which commercially available antiseptic is preferred for surgical scrubs because it continues to provide antimicrobial activity on the skin for some time after use?

A)Alcohol.
B)Chlorhexidine.
C)Hexachlorophene.
D)Chlorine.
E)Triclosan.

Question 28

The antiseptic most commonly used for disinfection of hands is

A)hexachlorophene.
B)chlorine.
C)triclosan.
D)alcohol.
E)glutaraldehyde.

Question 29

Which of the following antiseptics is commonly used for skin disinfection before surgery?

A)Hexachlorophene.
B)Povidone-iodine.
C)Triclosan.
D)Alcohol.
E)Glutaraldehyde.

Question 30

Which of the following influences the effectiveness of a chemical disinfection process?

A)Length of exposure time.
B)Concentration of disinfectant.
C)Number of bacteria present.
D)Presence of organic material.
E)All of the above.

Question 31

Which of the following is an effective disinfection process?

A)Boiling at 100⁰C for 5 minutes.
B)Boiling at 100⁰C for 30 minutes.
C)Heating to 63⁰C for 30 minutes.
D)Heating to 72⁰C for 15 seconds.
E)All of the above.

Question 32

Which of the following is the correct method of cleaning up a blood spill?

A)Wipe it up with disposable towels and wash the area with detergent.
B)Flood the spill with a phenolic compound,and wipe it up.
C)Flood the area with 0.1% sodium hypochlorite.
D)Wipe up the spill with disposable towels,and treat the area with 1.0% sodium hypochlorite.
E)Use a mop and a neutral detergent to decontaminate the area.

Question 33

Chemical disinfectants

A)do not guarantee total destruction of all microorganisms.
B)can be easily inactivated.
C)may be toxic to humans.
D)may take several minutes or more to work.
E)all of the above.

Question 34

Which of the following would be the most effective method for killing microorganisms in contaminated water?

A)Refrigeration.
B)Freezing.
C)Boiling.
D)All of the above.
E)None of the above.

Question 35

Ultraviolet light

A)can't kill microorganisms at all.
B)in sunlight has disinfecting activity.
C)can penetrate solid objects at close distances.
D)is not dependent on time of exposure for effectiveness.
E)none of the above.