MCQs on Sterilization and Disinfection - Decontamination, aseptic processes

1) Name all the common physical agents used for the sterilization process in the microbiology laboratories, hospitals, and biotechnology industries
a) Dry heat
b) Radiation
c) Steam heat
d) Phenols
e) Filtration

2) Which of the following is the recommended and required heat temperature and time period for the moist heat sterilization method used in an autoclave?
a) 180 c for 5 minutes
b) 121 c for 15 minutes
c) 126 c for 3 minutes     
d) 160 c for 45 minutes

3) What does the term 'Bioburden' means?
a) The number of microorganisms present in the surface
b) The bacterial spores present on the surface after the sterilization of the surface
c) The process of elimination of microorganisms by using physical agents
d) The aseptic process for the maintenance of the sterility of the surface

4) Which of the following best describes the process 'Disinfection'?
a) The elimination of all forms of microorganisms and bacterial spores
b) The elimination of all forms of bacterial spores
c) The reduction or elimination  of microorganisms and bacterial spores
d) The reduction or elimination of many microorganisms and some bacterial spores

5) Name the sterilization agent that is most frequently used in hospitals and clinical laboratories for the heat labile liquid substances or antibiotics
a) Dry heat
b) Radiation
c) Filtration
d) Formaldehyde 

6) Which of the following methods has been found safe and effective in the elimination of COVID-19? Select all that applies
a) Use of 60-70 % Ethyl alcohol
b) Use of antibacterial ointments
c) Hand wash with Soap and water
d) Intake of antibiotics when symptoms appear

7) Which of the following water purification method is most common in the rural parts of the countries like India, Nepal, Africa that is also a simple, reliable, and economical method?
a) Solar disinfection 
b) Chlorination
c) Advanced purifiers
d) Salt

8) All of the following chemical disinfectants used in laboratories and healthcare industries have been found to be effective against many bacteria, fungi, and viruses, Except?
a) Alcohols
b) Ethylene oxide
c) Formaldehyde
d) Chlorine
e) Steam heat

9) Which of the following sterilizing agent is found to have less or no sporicidal activity? Select all the correct options
a) Hot air oven
b) Ethyl alcohol
c) Pasteurization
d) Autoclave

10) Name the spore containing pathogen which shows resistance to heat and is usually not destroyed at 100 degrees Celcius or below 100 c
a) E. coli
b) Candida albicans
c) Vibrio cholera
d) Clostridium perfringens

11) Joseph Lister first introduced the use of antiseptics in hospitals, name the chemical he used for the antisepsis process
a) Ethyl alcohol
b) Carbolic acid
c) Hydrogen peroxide
d) Chlorohexidine

12) The Quality and Safety of products in pharmaceutical industries, food, and other biotechnology companies are mainly controlled by which of the following regulation departments in the USA?
a) Food and drug administration
b) International Standard Organization 9001
c) Good manufacturing practices
d) Center for Disease Control and prevention

13) Which of the following is the correct definition for the 'pasteurization' process of milk and fermented products?
a) The sterilization method that uses heat at a boiling temperature of 100 degrees Celcius
b) The sterilization method that uses heat at 100 to 120 degrees Celcius
c) The sterilization method that uses moist heat below 100 degrees Celcius
d) The sterilization method that uses moist heat above 100 degrees Celcius

14) Nonionizing radiation and ionizing radiation are sterilization methods mainly used in hospitals. Ultraviolet radiation is an example of nonionizing radiation, name the ionizing radiation
a) Infrared 
b) X-rays and gamma rays
c) Halogens
d) Ethylene oxide

15) Identify the temperature and time period commonly used for the hot air oven while sterilizing glassware in the laboratory
a) 180 degrees Celcius for 30 mins
b) 63 degrees Celcius for 30 mins
c) 121 degrees Celcius for 15 mins
d) 160 degrees Celcius for 45 mins

16) In 1996 in the USA there was an outbreak of enteric infection. Many children got infected by the consumption of juices, it was found that the particular juice company lack good sanitation practices and did not perform the pasteurization process. Name the causative bacteria that were isolated and identified from the beverage?
a) E. coli O157:H7
b) Vibrio cholerae
c) Bacillus subtilis
d) E. coli O121

17) Select all the common and widely used methods for drinking water treatment that helps in reducing the highly transmissible waterborne infections like typhoid and cholera
a) Boiling of the water
b) Using chlorine
c) Pasteurization process
d) Use of water filters

18) Sanitation has played a vital role in reducing the spread of the Covid-19 infection and other respiratory diseases. All of the following are the different sanitation practices that help in killing or reducing the viable pathogens, Except?
a) Handwashing and use of an oral mask for personal hygiene 
b) Use of chemical disinfectants to clean the surface area
c) Fumigation of area for the decontamination of air 
d) Getting the recommended vaccine shot against the diseases
e) Cleaning of objects with chemical agents

19) What is the correct meaning of the term known as terminal sterilization process?
a) The initial sterilization of the raw materials for the product
b) The final sterilization of the healthcare products and medical devices
c) The decontamination of the environmental bioburden
d) The aseptic technique used during the manufacturing process of the product 

20) Name the chemical which is an active ingredient of the 'bleach', a household decontamination product used to kill bacteria, fungi, and viruses?
a) Sodium chloride
b) Ethylene oxide
c) Sodium hypochlorite
d) Ethyl alcohol



Answers:
1- a), b), c), and e)
2- b) 121 c for 15 minutes
3- a)The number of microorganisms present in the surface
4- d)The reduction or elimination of many microorganisms and some bacterial spores
5- c) Filtration
6- a)Use of 60-70 % Ethyl alcohol and (c)Hand wash with Soap and water
7- a)Solar disinfection 
8- e) Steam heat
9- c) Pasteurization process - temperature below 100 degrees Celcius is used in the pasteurization process,  it does not help to kill or inhibit spores 
10- d) Clostridium perfringens
11-b) Carbolic acid
12-a) Food and drug administration
13-c) The sterilization method that uses moist heat below 100 degrees Celcius
14-b) X-rays and gamma rays
15-d) 160 degrees Celcius for 45 mins
16-a) E. coli O157:H7
17-a), b), and d)
18-d)Getting the recommended vaccine shot against the diseases - the vaccine is not the method of sanitation practices
19- b)The final sterilization of the healthcare products and medical devices
20- c) Sodium hypochlorite
































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