MOH Infection Control & Hospital Epidemiology 2 — Questions and Answers
Question 1: Which sterilization method is most appropriate for heat-sensitive medical devices such as flexible endoscopes?
- Steam autoclaving at 134°C
- Dry heat sterilization at 170°C
- Ethylene oxide (ETO) gas sterilization (Correct answer)
- Boiling at 100°C for 30 minutes
Correct answer: Ethylene oxide (ETO) gas sterilization
Ethylene oxide sterilization operates at low temperatures (~55°C) and is therefore suitable for heat-sensitive instruments that would be damaged by steam or dry heat.
Question 2: According to the Spaulding classification, a device that contacts intact mucous membranes but does not penetrate sterile tissue is classified as:
- Critical
- Semi-critical (Correct answer)
- Non-critical
- Sterile
Correct answer: Semi-critical
Semi-critical items (e.g., laryngoscope blades, respiratory therapy equipment) contact intact mucous membranes and require at minimum high-level disinfection.
Question 3: A patient colonized with MRSA (Methicillin-resistant Staphylococcus aureus) should be placed under which precautions?
- Airborne precautions in a negative-pressure room
- Droplet precautions with a surgical mask
- Contact precautions with gloves and gown (Correct answer)
- Standard precautions only
Correct answer: Contact precautions with gloves and gown
MRSA spreads primarily through direct contact; contact precautions (gloves and gown) are required to prevent transmission to other patients and staff.
Question 4: The most important modifiable risk factor for catheter-associated urinary tract infections (CAUTI) is:
- Poor sterile technique during catheter insertion
- Prolonged duration of urinary catheter use (Correct answer)
- Use of an incorrect catheter size
- Irrigating the catheter with tap water
Correct answer: Prolonged duration of urinary catheter use
Prolonged catheterization is the strongest modifiable risk factor for CAUTI; daily review and prompt removal when no longer indicated is the key preventive strategy.
Question 5: Which intervention is most effective in preventing ventilator-associated pneumonia (VAP)?
- Placing the patient in a flat supine position
- Elevating the head of bed to 30–45 degrees (Correct answer)
- Changing ventilator circuits every 24 hours
- Administering prophylactic systemic antibiotics routinely
Correct answer: Elevating the head of bed to 30–45 degrees
Semi-recumbent positioning (30–45° head elevation) reduces gastric reflux and microaspiration of oropharyngeal secretions into the lower respiratory tract, significantly lowering VAP rates.
Question 6: An N95 respirator (rather than a standard surgical mask) is required when caring for a patient with:
- Hepatitis B
- Active pulmonary tuberculosis (Correct answer)
- Influenza
- Clostridium difficile infection
Correct answer: Active pulmonary tuberculosis
Active pulmonary TB produces airborne droplet nuclei that are small enough to bypass a surgical mask; an N95 respirator that filters ≥95% of airborne particles is therefore required.
Question 7: The correct sequence for doffing (removing) PPE to minimize self-contamination is:
- Gloves → Gown → Eye protection → Mask/respirator (Correct answer)
- Mask → Gloves → Gown → Eye protection
- Gown → Gloves → Eye protection → Mask
- Eye protection → Mask → Gown → Gloves
Correct answer: Gloves → Gown → Eye protection → Mask/respirator
Gloves (the most contaminated item) are removed first, followed by the gown, then eye protection, and finally the mask/respirator, with hand hygiene between each step.
MOH Infection Control & Hospital Epidemiology 2
Which sterilization method is most appropriate for heat-sensitive medical devices such as flexible endoscopes?