Free Infection Control and Sterilisation MCQs with Answers

• A. Gamma-Rays
• B. X-Rays
• C. Autoclaving
• D. Boiling

Explanation: Gamma irradiation is used industrially to sterilise prepackaged surgical needles and sutures because it penetrates sealed materials and…

• A. Robert Koch
• B. Joeph Lister
• C. John Hunter
• D. Alexander flemings

Explanation: Joseph Lister introduced antiseptic surgical practice, which is commonly credited in basic microbiology questions with establishing…

• A. Autoclaving
• B. Hot air oven
• C. Inspissation
• D. Tyndallization

Explanation: Dry dressing powders are sterilised in a hot-air oven because they may be damaged by moisture and are unsuitable for steam penetration.

• A. Brucella
• B. Mycobacterium
• C. Salmonella
• D. Coxiella burnetti

Explanation: Coxiella burnetii is unusually resistant to heat and may survive ordinary pasteurisation conditions, so it requires more stringent…

• A. Using chemical indicator strip or pouch
• B. Recording a temperature/ pressure readings from sterilizer guage
• C. Using a bacterial spore test
• D. Determining the ability of a sterilizer to kill the hepatitis B virus

Explanation: A bacterial spore test is the best practical indicator because resistant spores directly demonstrate whether the sterilisation process can…

• A. Autoclaving
• B. Hot air oven
• C. Incineration
• D. Formaldehyde

Explanation: Glassware is usually sterilised in a hot-air oven because dry heat avoids moisture and is suitable for glass and other heat-stable…

• A. Carbolic acid spraying
• B. Washing with soap and water
• C. Formaldehyde fumigation
• D. ETO gas

Explanation: Formaldehyde fumigation is used to disinfect and sterilize enclosed areas such as operation theatres, including surfaces and air.

• A. Incineration
• B. Dumping
• C. Autoclaving
• D. Burying

Explanation: Incineration destroys contaminated dressings by burning them at high temperature, reducing both pathogens and waste volume.

• A. using Bacillus stearo thermo philus
• B. Using non-pathogenic strain of clostridium tetani
• C. Using chemical indicator
• D. Using methylene blue

Explanation: Bacillus stearothermophilus, now called Geobacillus stearothermophilus, is used as a biological indicator for moist-heat sterilisation…

• A. Vegetative forms
• B. Spore forms
• C. Both of the above
• D. None of the above

Explanation: Disinfection destroys or removes many vegetative microorganisms from surfaces but does not reliably destroy bacterial spores.

• A. 140°C x 2 hrs. x 10 lbs pr.
• B. 121°F x 15 mts. x 15 lbs pr.
• C. 121°F x 15 sec. x 15 lbs pr.
• D. 121°C 15 mts. x 15 lbs pr.

Explanation: The standard autoclave cycle is 121°C at about 15 psi for 15 minutes, allowing saturated steam to destroy microorganisms and spores.

• A. Kill mircobes
• B. Remove microbes
• C. Inhibit microbial growth
• D. Dehydrate microbial cells

Explanation: Soap mainly lifts microbes, oils, and organic material from the skin so they can be removed by rinsing; it does not necessarily kill them.

• A. Disinfectant
• B. Moist heat sterilisation
• C. Antibiotics
• D. Dry heat sterilization

Explanation: The Rideal-Walker test measures a disinfectant's efficiency by comparing its activity with phenol, producing a phenol coefficient.

• A. Pathogens killed but spores are not affected
• B. Only pathogenic micro-organisms killed
• C. Non-pathogenic killed
• D. All pathogenic and non-pathogenic microorganisms killed

Explanation: Sterilisation means complete destruction or removal of all forms of microbial life, including pathogenic and non-pathogenic organisms and…

• A. Boiling at 100°C
• B. Disinfection by hypochlorite solution
• C. Autoclave
• D. Pasteurisation

Explanation: A properly operated autoclave destroys bacterial spores through saturated steam under pressure, typically at 121°C.

• A. 3 minutes
• B. 15 minutes
• C. 30 minutes
• D. 60 minutes

Explanation: At 134°C, a pre-vacuum autoclave can sterilize properly prepared surgical instruments in about 3 minutes.

• A. Pasteurization
• B. Autoclave
• C. Kochs sterilizer
• D. hot air oven

Explanation: An autoclave uses saturated steam under pressure, raising the temperature above the normal boiling point and denaturing microbial…

• A. Gram positive organisms
• B. Gram negative organisms
• C. Mycoplasma
• D. Virus infections

Explanation: ICU-acquired pneumonias are classically dominated by Gram-negative bacilli, including Pseudomonas, Klebsiella and Acinetobacter, although…