MDRAO High-Level Disinfection 1 — Questions and Answers
Question 1: High-level disinfection (HLD) is defined as the destruction of all microorganisms EXCEPT:
- Vegetative bacteria
- Mycobacteria
- Lipid viruses
- High numbers of bacterial spores (Correct answer)
Correct answer: High numbers of bacterial spores
HLD kills all microorganisms including vegetative bacteria, mycobacteria, fungi, and viruses, but may not destroy high numbers of bacterial spores.
Question 2: According to the Spaulding classification, which category of medical devices requires at minimum high-level disinfection?
- Critical items
- Semi-critical items (Correct answer)
- Non-critical items
- Non-contact items
Correct answer: Semi-critical items
Semi-critical items contact mucous membranes or non-intact skin and require at minimum high-level disinfection.
Question 3: Which chemical agent has historically been the most widely used for high-level disinfection of flexible endoscopes?
- Peracetic acid
- Hydrogen peroxide
- Glutaraldehyde (Correct answer)
- Sodium hypochlorite
Correct answer: Glutaraldehyde
Glutaraldehyde (e.g., Cidex) has been the most widely used HLD agent for flexible endoscopes due to its broad-spectrum activity and material compatibility.
Question 4: What does MEC stand for in the context of high-level disinfectant solutions?
- Maximum Effective Concentration
- Minimum Effective Concentration (Correct answer)
- Microbial Elimination Count
- Minimum Exposure Cycle
Correct answer: Minimum Effective Concentration
MEC stands for Minimum Effective Concentration, the lowest concentration at which a disinfectant solution still achieves high-level disinfection.
Question 5: Why must items be thoroughly cleaned before high-level disinfection?
- To prevent chemical reactions with the HLD agent
- To remove organic material that can inactivate the disinfectant (Correct answer)
- To reduce the temperature of the solution
- To comply with documentation requirements only
Correct answer: To remove organic material that can inactivate the disinfectant
Organic material such as blood and protein inactivates HLD agents, preventing them from contacting and killing microorganisms on device surfaces.
Question 6: Which personal protective equipment (PPE) is MOST important when manually handling glutaraldehyde solutions?
- Shoe covers and a gown
- Chemical-resistant gloves, face shield, and gown (Correct answer)
- Surgical mask and exam gloves
- Safety glasses and a lab coat only
Correct answer: Chemical-resistant gloves, face shield, and gown
Glutaraldehyde is a sensitizer and irritant; chemical-resistant gloves, a face shield, and a fluid-resistant gown protect against skin, eye, and respiratory exposure.
Question 7: What is the FIRST step a technician must perform before placing a device into a high-level disinfectant solution?
- Check the solution expiry/reuse date
- Test the MEC of the solution (Correct answer)
- Rinse the device with sterile water
- Document the batch number
Correct answer: Test the MEC of the solution
Testing the MEC with an appropriate test strip before each use confirms the solution is still at or above the minimum effective concentration required for HLD.
MDRAO High-Level Disinfection 1
High-level disinfection (HLD) is defined as the destruction of all microorganisms EXCEPT: