CABT Sterilization and Infection Control 1 — Questions and Answers
Question 1: What is the most widely used sterilization method for heat-stable medical instruments in healthcare facilities?
- Ethylene oxide gas sterilization
- Steam autoclave (moist heat sterilization) (Correct answer)
- Dry heat oven sterilization
- Gamma radiation sterilization
Correct answer: Steam autoclave (moist heat sterilization)
Steam autoclave (moist heat) is the most widely used sterilization method because it is effective, fast, non-toxic, and economical for heat-stable instruments.
Question 2: What temperature and pressure are maintained during a standard gravity displacement steam sterilization cycle?
- 100°C (212°F) at standard atmospheric pressure
- 110°C (230°F) at 5 psi
- 121°C (250°F) at 15 psi (Correct answer)
- 134°C (273°F) at 30 psi
Correct answer: 121°C (250°F) at 15 psi
Standard gravity displacement steam sterilization is conducted at 121°C (250°F) at 15 psi for the required exposure time to ensure microbial kill.
Question 3: According to the Spaulding Classification System, surgical instruments that enter sterile tissue or the vascular system are classified as:
- Non-critical items
- Semi-critical items
- Critical items (Correct answer)
- High-risk environmental items
Correct answer: Critical items
Critical items contact sterile tissue or the vascular system and must be sterilized to prevent the highest risk of infection transmission.
Question 4: Ethylene oxide (EtO) sterilization is best suited for which type of medical equipment?
- Metal surgical instruments requiring rapid turnaround
- Heat and moisture-sensitive devices that cannot withstand steam (Correct answer)
- Implants requiring ionizing radiation processing
- Liquid medications needing aseptic filtration
Correct answer: Heat and moisture-sensitive devices that cannot withstand steam
EtO sterilizes at low temperatures without moisture, making it ideal for heat and moisture-sensitive devices such as plastics and electronics.
Question 5: Which biological indicator organism is the standard for testing the efficacy of steam sterilization?
- Bacillus atrophaeus spores
- Clostridium difficile spores
- Geobacillus stearothermophilus spores (Correct answer)
- Staphylococcus aureus cultures
Correct answer: Geobacillus stearothermophilus spores
Geobacillus stearothermophilus spores are highly resistant to moist heat and are the accepted standard biological indicator for steam sterilization monitoring.
Question 6: The Sterility Assurance Level (SAL) required for medical devices labeled as 'sterile' is:
- 10⁻³ (1 in 1,000)
- 10⁻⁴ (1 in 10,000)
- 10⁻⁵ (1 in 100,000)
- 10⁻⁶ (1 in 1,000,000) (Correct answer)
Correct answer: 10⁻⁶ (1 in 1,000,000)
The required SAL for sterile medical devices is 10⁻⁶, meaning no more than a 1 in 1,000,000 probability of a viable microorganism surviving sterilization.
Question 7: Why is thorough cleaning performed before sterilization or disinfection of medical instruments?
- Cleaning alone achieves sterilization for most instruments
- It neutralizes chemical residues from previous procedures
- Organic debris can shield microorganisms and impair sterilant penetration (Correct answer)
- It activates the germicidal properties of the sterilizing agent
Correct answer: Organic debris can shield microorganisms and impair sterilant penetration
Organic debris such as blood and tissue physically protects microorganisms from sterilants and blocks penetration of the sterilizing agent, making pre-cleaning essential.
CABT Sterilization and Infection Control 1
What is the most widely used sterilization method for heat-stable medical instruments in healthcare facilities?