CBET Sterilization and Infection Control Equipment 4 — Questions and Answers
Question 1: Which biological indicator organism is used to validate ethylene oxide (EtO) sterilization cycles?
- Geobacillus stearothermophilus
- Bacillus atrophaeus (Correct answer)
- Clostridium sporogenes
- Staphylococcus aureus
Correct answer: Bacillus atrophaeus
Bacillus atrophaeus spores are the standard biological indicator for EtO sterilization validation.
Question 2: A steam autoclave fails its Bowie-Dick test. What is the most likely cause?
- Inadequate sterilization time
- Air entrapment in the chamber (Correct answer)
- Insufficient chemical indicator concentration
- Overloading of instrument trays
Correct answer: Air entrapment in the chamber
The Bowie-Dick test detects air removal failures; a failed test indicates residual air is preventing steam penetration.
Question 3: What is the primary advantage of low-temperature hydrogen peroxide plasma sterilization over EtO?
- Lower cost per cycle
- No toxic residuals requiring aeration (Correct answer)
- Longer shelf life for sterile packages
- Effective on all plastics including polyethylene
Correct answer: No toxic residuals requiring aeration
Hydrogen peroxide plasma leaves no toxic residuals, eliminating the lengthy aeration period required after EtO sterilization.
Question 4: Which parameter is NOT directly monitored during a standard steam sterilization cycle?
- Temperature
- Pressure
- Humidity (Correct answer)
- Exposure time
Correct answer: Humidity
Standard steam sterilization monitoring focuses on temperature, pressure, and time; humidity is a critical parameter for EtO, not steam cycles.
Question 5: An ultrasonic cleaner used for pre-sterilization cleaning operates primarily through which mechanism?
- High-temperature water jets
- Acoustic cavitation (Correct answer)
- Chemical enzyme action
- Pressurized detergent spray
Correct answer: Acoustic cavitation
Ultrasonic cleaners work via acoustic cavitation, where rapidly forming and collapsing bubbles dislodge debris from instrument surfaces.
Question 6: When performing a spore test on a tabletop autoclave, how often does AAMI recommend routine biological monitoring?
- Daily
- Weekly (Correct answer)
- Monthly
- With every load
Correct answer: Weekly
AAMI ST55 recommends at minimum weekly spore testing for tabletop steam sterilizers used in healthcare settings.
Question 7: Which type of packaging material is incompatible with hydrogen peroxide plasma sterilization?
- Tyvek pouches
- Polypropylene wraps
- Paper/cellulose-based wraps (Correct answer)
- Polyester pouches
Correct answer: Paper/cellulose-based wraps
Cellulose-based materials absorb hydrogen peroxide, depleting the sterilant and causing cycle failures in plasma sterilizers.
CBET Sterilization and Infection Control Equipment 4
Which biological indicator organism is used to validate ethylene oxide (EtO) sterilization cycles?