Free MDRAO Microbiology and Infection Control Questions and Answers 1 — Questions and Answers
Question 1: Which of the following microorganisms is the most resistant to sterilization processes?
- Viruses.
- Fungi.
- Vegetative bacteria.
- Bacterial spores. (Correct answer)
Correct answer: Bacterial spores.
Bacterial spores are the dormant, highly resistant form of certain bacteria. Sterilization processes are specifically designed to be powerful enough to kill these spores, with the assurance that anything less resistant will also be destroyed.
Question 2: In the chain of infection, what is the role of a contaminated surgical instrument?
- A susceptible host.
- A portal of entry.
- A mode of transmission (fomite). (Correct answer)
- An infectious agent.
Correct answer: A mode of transmission (fomite).
A contaminated object, like a surgical instrument, is known as a fomite. It serves as the vehicle, or mode of transmission, that carries the infectious agent (e.g., bacteria) from a reservoir to a susceptible host, thus continuing the chain of infection.
Question 3: What is the primary purpose of cleaning medical devices prior to sterilization?
- To make the instruments shiny.
- To remove all microorganisms, including spores.
- To remove soil and bioburden, which can shield microbes from the sterilant. (Correct answer)
- To cool the instruments down after use.
Correct answer: To remove soil and bioburden, which can shield microbes from the sterilant.
Cleaning is the critical first step in reprocessing to remove all visible soil and bioburden. If not removed, this organic and inorganic matter can shield microorganisms from the sterilant, preventing it from reaching the device surface and leading to sterilization failure.
Question 4: When working in the decontamination area, what is the minimum required Personal Protective Equipment (PPE)?
- A lab coat and safety glasses.
- Fluid-resistant gown, gloves, face shield or goggles/mask, and shoe covers. (Correct answer)
- A simple surgical mask and gloves.
- Scrubs and a hair cover.
Correct answer: Fluid-resistant gown, gloves, face shield or goggles/mask, and shoe covers.
The decontamination area poses a high risk of exposure to pathogens through splashes and aerosols. Comprehensive PPE is required to protect the technician's skin, clothing, and mucous membranes. This includes a fluid-resistant gown, utility gloves, a full face shield (or goggles and mask), and fluid-resistant shoe covers.
Question 5: A semi-critical medical device, such as a flexible endoscope, requires what minimum level of reprocessing?
- Low-level disinfection.
- High-level disinfection. (Correct answer)
- Sterilization.
- Simple cleaning with soap and water.
Correct answer: High-level disinfection.
Semi-critical devices are those that contact mucous membranes or non-intact skin. According to the Spaulding Classification, these items require, at a minimum, high-level disinfection (HLD) to eliminate all vegetative microorganisms, mycobacteria, fungi, and viruses.
Question 6: Prions, the causative agent for Creutzfeldt-Jakob Disease (CJD), are exceptionally resistant to:
- Manual washing with detergents.
- Standard steam sterilization cycles. (Correct answer)
- Cool temperatures.
- Air drying.
Correct answer: Standard steam sterilization cycles.
Prions are misfolded proteins that are not living organisms, making them extremely resistant to conventional sterilization methods. Special, extended steam sterilization cycles (e.g., 134°C for 18 minutes) and specific chemical treatments are required to effectively inactivate them on medical devices.
Question 7: What is a biofilm?
- A type of wrapping material used for sterilization.
- A community of microorganisms attached to a surface and encased in a protective slime layer. (Correct answer)
- The report generated by a biological indicator.
- A thin, transparent plastic film used to cover instrument trays.
Correct answer: A community of microorganisms attached to a surface and encased in a protective slime layer.
A biofilm is a complex, protected colony of microbes that adhere to surfaces, especially inside lumens of medical devices. The slimy matrix they create acts as a shield, making them highly resistant to cleaning, disinfection, and sterilization, which poses a significant challenge in reprocessing.
Free MDRAO Microbiology and Infection Control Questions and Answers 1
Which of the following microorganisms is the most resistant to sterilization processes?