MDRAO - Medical Device Reprocessing Association of Ontario Sterilization Methods and Monitoring Questions and Answers — Questions and Answers
Question 1: A Class 5 chemical indicator is used to monitor a steam sterilization cycle. What does a successful color change on this indicator signify?
- That the pack has been exposed to the sterilization process.
- That all critical parameters of the sterilization cycle (time, temperature, and steam) have been met. (Correct answer)
- That the sterilizer is effectively removing air from the chamber.
- That there is no microbial growth within the processed load.
Correct answer: That all critical parameters of the sterilization cycle (time, temperature, and steam) have been met.
A Class 5 chemical indicator, also known as an integrating indicator, is designed to react to all critical variables of the steam sterilization process: time, temperature, and the presence of saturated steam. A correct color change provides assurance that these conditions were met inside the pack, correlating with the conditions required to kill a biological indicator.
Question 2: A medical device reprocessing technician is preparing a load for a low-temperature vaporized hydrogen peroxide (VH2O2) sterilizer. Which biological indicator is most appropriate for monitoring the efficacy of this sterilization method?
- Bacillus atrophaeus
- Bacillus subtilis
- Geobacillus stearothermophilus (Correct answer)
- Clostridium sporogenes
Correct answer: Geobacillus stearothermophilus
Geobacillus stearothermophilus spores are highly resistant to both steam and vaporized hydrogen peroxide (VH2O2) sterilization processes. For this reason, they are the standard microorganism used in biological indicators to monitor the effectiveness of these sterilization methods.
Question 3: A single, wrapped instrument is dropped on the floor in the operating room and is needed urgently for the ongoing procedure. Which of the following is the most appropriate action according to Canadian standards?
- Wipe the instrument with a disinfectant and hand it to the surgeon.
- Send the instrument for Immediate-Use Steam Sterilization (IUSS) following all required cleaning and decontamination steps. (Correct answer)
- The instrument cannot be used and a sterile replacement must be found.
- Rinse the instrument with sterile water and place it back on the sterile field.
Correct answer: Send the instrument for Immediate-Use Steam Sterilization (IUSS) following all required cleaning and decontamination steps.
Immediate-Use Steam Sterilization (IUSS), formerly known as flash sterilization, should be kept to a minimum and used only in situations where there is insufficient time to process an item by the preferred terminal sterilization method. The instrument must first be properly cleaned and decontaminated before undergoing the IUSS cycle. Wiping with a disinfectant or rinsing is insufficient, and if a sterile replacement is unavailable, IUSS is the appropriate emergency response.
Question 4: What is the primary purpose of performing a Bowie-Dick test in a pre-vacuum steam sterilizer?
- To confirm the sterilizer reaches the programmed temperature.
- To validate the lethality of the sterilization cycle against resistant spores.
- To detect air leaks and ensure adequate air removal from the chamber. (Correct answer)
- To verify that the drying time is sufficient for the load.
Correct answer: To detect air leaks and ensure adequate air removal from the chamber.
The Bowie-Dick test is a Class 2 chemical indicator used specifically to monitor the effectiveness of the air removal (pre-vacuum) stage of a pre-vacuum steam sterilizer. Inadequate air removal can create air pockets that prevent steam from contacting all surfaces of the load, leading to sterilization failure. The test does not confirm temperature or kill spores directly but ensures the conditions for effective steam penetration are met.
Question 5: Which of the following sterilization methods is most suitable for processing heat-sensitive and moisture-sensitive flexible endoscopes?
- Dry heat sterilization
- Pre-vacuum steam sterilization
- Peracetic acid liquid sterilization (Correct answer)
- Gravity displacement steam sterilization
Correct answer: Peracetic acid liquid sterilization
Peracetic acid liquid sterilization is a low-temperature method that is safe for heat-sensitive and moisture-sensitive devices like flexible endoscopes. It uses a chemical sterilant at a relatively low temperature (around 50°C) to achieve sterilization without damaging the delicate components of the endoscope. Steam and dry heat methods operate at high temperatures that would destroy the device.
Question 6: When monitoring a sterilization load, what type of monitoring provides a direct measure of the lethality of the process?
- Mechanical monitoring (printouts)
- Chemical indicators
- Biological indicators (Correct answer)
- Physical monitoring (gauges)
Correct answer: Biological indicators
Biological indicators (BIs) are the only method that directly monitors the lethality of the sterilization process because they contain a known population of highly resistant microorganisms (e.g., Geobacillus stearothermophilus). If the BI test is negative after incubation, it provides a high level of assurance that the sterilization process was effective in killing all microorganisms. Mechanical and chemical monitors verify that the physical parameters of the cycle were met, but do not directly prove microbial kill.
MDRAO - Medical Device Reprocessing Association of Ontario Sterilization Methods and Monitoring Questions and Answers
A Class 5 chemical indicator is used to monitor a steam sterilization cycle.
What does a successful color change on this indicator signify?