MCQs on Sterilization and Disinfection - Decontamination, aseptic processes, safety precautions in laboratory and hospitals

                                Sterilization, disinfection, and aseptic procedure

1) Identify all the commonly used physical methods for the sterilization process in healthcare facilities including microbiology laboratories, hospitals, and biotechnology industries
a) Dry heat
b) Ionizing gamma Radiation
c) Moist heat (steam under pressure)
d) Phenols
e) Filtration

2) Autoclave is a widely used equipment for the sterilization process in microbiology laboratory, it is an example of moist heat method.
Which of the following is the recommended heat temperature and time period for the moist heat sterilization process conducted in an autoclave?
a) 180 degree C for 5 minutes
b) 121 degree C for 15 minutes
c) 126 degree C for 3 minutes     
d) 160 degree C for 45 minutes

3) What is the correct statement for the term 'Bioburden'?
a) The number of microorganisms present on 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 of '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 method that is frequently used in hospitals and clinical laboratories for the heat-labile or heat-sensitive materials such as 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 virus? 
Select all that apply:
a) Use of 60-70 % isopropyl alcohol
b) Use of antibacterial ointments
c) Hand wash with Soap and water
d) Intake of antibiotics when symptoms appear

7) In rural areas of countries like India, Nepal, and Africa, which of the following method is prevalent, dependable, and cost-effective approach for water purification process?
a) Solar disinfection 
b) Chlorination
c) Advanced purifiers
d) Salt use

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 the pathogen which shows resistance to heat and is usually not destroyed by using heat at 100 degrees Celcius.
a) E. coli
b) Candida albicans
c) Vibrio cholera
d) Clostridium perfringens

11) Joseph Lister first introduced the use of antiseptics in hospitals, what is the name of 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 one 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) An outbreak of enteric infection occurred in 1996 in the USA. Numerous children got sick after the consumption of a specific juice company, investigation was done and the reports showed lack of good sanitation practices and elimination of the pasteurization process by that company, this led to foodborne infection.
Name the bacteria identified as the cause of the outbreak?
a) E. coli O157:H7
b) Vibrio cholerae
c) Bacillus subtilis
d) E. coli O121

17) Select all the common and effective methods that can help in reducing the highly transmissible waterborne infections like typhoid and cholera.
a) Boiling of the water
b) Using chlorine for purification
c) Pasteurization process
d) Use of water filters

18) Good sanitation practices have played a vital role in reducing the spread of Covid-19 infection and other respiratory diseases. 
All of the following are important sanitation practices that can help in killing or reducing 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 disease
e) Cleaning of objects with chemical agents

19) What is the correct meaning of the term known as the '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 in a 'bleach' (a disinfectant) used to eliminate bacteria, fungi, and viruses?
a) Sodium chloride
b) Ethylene oxide
c) Sodium hypochlorite
d) Ethyl alcohol

21) Which of the following is a recommended method for sterilizing surgical instruments?
a) Wiping with alcohol
b) Cleaning with soap and water 
c) Autoclaving 
d) Soaking in disinfectant solution 

22) What is the minimum recommended concentration of bleach for disinfection purposes in healthcare facilities, home spaces and public places?
a) 5% 
b) 10% 
c) 50% 
d) 100%

23) Select all the common and effective 'physical disinfection method' used for the elimination of pathogens?
a) Boiling (100 degrees Celsius for 15 minutes)
b) Pasteurization (70 degrees Celsius for 30 minutes)
c) Ultraviolet rays (nonionizing radiation)
d) Alcohols

24) Which of the following is the standard safety precautions that is required and essential while working in the laboratory?
a) Avoid mouth pipetting
b) Avoid eating or chewing in the lab
c) Thoroughly wash hands and other skin surfaces after removing gloves and immediately after any contamination
d) Always wear proper Protective Personal equipment (PPE)
e) All of the above

25) All of the following statements are correct regarding the Biological Safety Cabinet in a microbiology laboratory, Except?
a) Used while handling hazardous microorganisms
b) Categorized into three classes (I, II and III)
c) Consists of UV light, HEPA filters for sterilization
d) Standard Personal protective equipment (PPE) may not be required while using the cabinet

26) Which containment level is appropriate for handling microorganisms that pose the highest risk to laboratory personnel and the environment?
a. BSL-1
b. BSL-2
c. BSL-3
d. BSL-4

27) Which organization sets safety standards and guidelines for laboratories in the United States?
a) CDC (Centers for Disease Control and Prevention)
b) EPA (Environmental Protection Agency)
c) OSHA (Occupational Safety and Health Administration)
d) WHO (World Health Organization)

Answers with Explanation:
1- a), b), c), and e). 
Phenol or carbolic acid/phenolic acid is a chemical used for disinfection method.

2- b) 121 c for 15 minutes. Moist heat utilizes steam under pressure in autoclaves for more effective sterilization.
3- a)The number of microorganisms present on the surface

4- d)The reduction or elimination of many microorganisms and some bacterial spores
Sterilization process eliminates all microorganisms and bacterial spores but disinfection process may not eliminate bacterial spores.

5- c) Filtration, it is a sterilization method used to remove microorganisms from heat-sensitive solutions or gases that cannot be sterilized by heat.

6- a)Use of 60-70 % isopropyl 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 Celsius 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 Celsius
14-b) X-rays and gamma rays
15-d) 160 degrees Celsius for 45 mins
16-a) E. coli O157:H7
17-a), b), and d)
18-d)Getting the recommended vaccine shot against the disease - 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
          21- c) Autoclaving, the high pressure and high temperature method in autoclaving effectively                          kills all microorganisms including bacterial spores.

          22- b) 10%, the recommended concentration is strong enough to eliminate microorganisms on                           surface.

          23- a) Boiling (100 degrees Celsius for 15 minutes), b) Pasteurization (70 degrees Celsius                             for 30 minutes), and c) Ultraviolet rays (nonionizing radiation)
                d) Alcohols are used as 'chemical disinfection method'.
         24- e) All of the above
         25- d) Standard PPE may not be required while using the cabinet
         26- d) BSL-4. BSL-4 agents are considered high risk and cause life                                                                      threatening disease.
         27- c) OSHA (Occupational Safety and Health Administration). It is a federal agency within                      the United States Department of Labor. OSHA's primary mission is to ensure safe and                              healthy working conditions for employees in the United States by enforcing workplace                            safety and health regulations.


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