CBET Sterilization and Infection Control Equipment 5 — Questions and Answers
Question 1: A gravity displacement autoclave is unable to sterilize items with long narrow lumens because:
- The temperature exceeds safe limits for lumened devices
- Air cannot be fully displaced from enclosed spaces by gravity alone (Correct answer)
- Steam pressure is insufficient for penetration
- Cycle time is too short for hollow instruments
Correct answer: Air cannot be fully displaced from enclosed spaces by gravity alone
Gravity displacement relies on steam displacing air downward, but trapped air in lumens prevents steam contact with internal surfaces.
Question 2: What does the D-value represent in sterilization science?
- The minimum dose required to kill all microorganisms
- The time or dose needed to reduce the microbial population by 90% (Correct answer)
- The depth of penetration of the sterilant
- The detection threshold of biological indicators
Correct answer: The time or dose needed to reduce the microbial population by 90%
The D-value (decimal reduction value) is the time or radiation dose required to reduce a microbial population by one log (90%).
Question 3: Which class of chemical indicators provides the most information about sterilization cycle conditions?
- Class 1 (process indicators)
- Class 3 (single-variable indicators)
- Class 5 (integrating indicators)
- Class 6 (emulating indicators) (Correct answer)
Correct answer: Class 6 (emulating indicators)
Class 6 emulating indicators react to all critical parameters of a specific sterilization cycle and are the most informative chemical indicators.
Question 4: During vaporized hydrogen peroxide (VHP) sterilization, which condition causes cycle failure?
- Excessive load mass
- Residual moisture in the chamber or on devices (Correct answer)
- Low ambient room temperature
- Use of metallic instrument trays
Correct answer: Residual moisture in the chamber or on devices
Residual moisture reacts with and depletes hydrogen peroxide vapor, reducing sterilant concentration below effective levels.
Question 5: A HEPA filter used in a biological safety cabinet must retain what minimum percentage of particles at 0.3 microns?
- 95%
- 97%
- 99.97% (Correct answer)
- 99.999%
Correct answer: 99.97%
HEPA filters are defined by their ability to capture at least 99.97% of particles at the most penetrating particle size of 0.3 microns.
Question 6: Which sterilization method is most appropriate for heat-sensitive fiber optic endoscopes that cannot be immersed?
- Flash steam sterilization
- Ethylene oxide gas sterilization (Correct answer)
- Gamma radiation
- Dry heat sterilization
Correct answer: Ethylene oxide gas sterilization
EtO sterilization operates at low temperatures and can process complex heat-sensitive devices including non-immersible optics.
Question 7: The sterility assurance level (SAL) required for critical medical devices classified by the Spaulding system is:
- 10⁻³
- 10⁻⁴
- 10⁻⁶ (Correct answer)
- 10⁻⁸
Correct answer: 10⁻⁶
A SAL of 10⁻⁶ is the regulatory standard for critical devices, meaning a one-in-a-million probability of a viable organism remaining.
CBET Sterilization and Infection Control Equipment 5
A gravity displacement autoclave is unable to sterilize items with long narrow lumens because: