HSPA Biological and Chemical Indicators 2 — Questions and Answers
Question 1: What is the correct incubation time and temperature for steam sterilization biological indicators?
- 24 hours at room temperature
- As specified by the BI manufacturer, typically 24-48 hours at 55-60 degrees Celsius for conventional BIs, or as fast as 20-60 minutes for rapid-read BIs (Correct answer)
- 1 hour at 37 degrees Celsius
- 7 days at 35 degrees Celsius
Correct answer: As specified by the BI manufacturer, typically 24-48 hours at 55-60 degrees Celsius for conventional BIs, or as fast as 20-60 minutes for rapid-read BIs
Conventional BIs require 24-48 hours of incubation at 55-60 degrees Celsius (the optimal growth temperature for G. stearothermophilus). Rapid-read BIs use fluorescent enzyme detection to provide results in as little as 20-60 minutes. Always follow the specific manufacturer's instructions for incubation time and temperature.
Question 2: What does a positive biological indicator result after sterilization indicate?
- The sterilizer is working correctly
- The sterilization cycle failed to kill the test spores, indicating a potential sterilization failure that requires immediate investigation (Correct answer)
- The BI was defective
- The incubator malfunctioned
Correct answer: The sterilization cycle failed to kill the test spores, indicating a potential sterilization failure that requires immediate investigation
A positive BI (spore growth detected) indicates that the sterilization cycle did not achieve conditions lethal to the test organisms. This is a potential sterilization failure requiring immediate response: quarantine all items from that load, recall items already distributed if possible, investigate the cause, and do not use the sterilizer until the issue is resolved.
Question 3: What is the purpose of a control biological indicator?
- To test the sterilizer before the first use of the day
- To verify that the spore population on the unexposed BI is viable, confirming that a negative test result is meaningful rather than due to non-viable spores (Correct answer)
- To calibrate the incubator temperature
- To test the cleaning solution's effectiveness
Correct answer: To verify that the spore population on the unexposed BI is viable, confirming that a negative test result is meaningful rather than due to non-viable spores
A control BI from the same lot is incubated without being exposed to sterilization. If the control grows positive (spores are viable), it confirms that the spore population was alive and capable of growth. This validates that a negative result from the processed BI represents actual spore kill, not simply dead spores that were never viable.
Question 4: What is a Class 6 emulating chemical indicator?
- The same as a Class 5 integrating indicator
- A cycle-specific indicator designed to react to all critical variables for a specific sterilization cycle type, providing a pass/fail result for that specific cycle (Correct answer)
- An external indicator for package identification
- A biological indicator alternative that uses chemicals instead of spores
Correct answer: A cycle-specific indicator designed to react to all critical variables for a specific sterilization cycle type, providing a pass/fail result for that specific cycle
Class 6 emulating indicators are designed to respond to all critical parameters of one specific type of sterilization cycle. They provide a pass/fail result indicating whether the specific cycle parameters were met. Unlike Class 5 integrators that work across multiple cycle types, Class 6 indicators are cycle-specific and provide the most stringent chemical indicator assessment.
Question 5: Where should an internal chemical indicator be placed within a sterilization pack?
- On top of the instruments where it is easily visible
- In the area most challenging for sterilant to penetrate, typically the geometric center of the pack (Correct answer)
- Outside the wrapping material
- Anywhere inside the pack; position does not matter
Correct answer: In the area most challenging for sterilant to penetrate, typically the geometric center of the pack
Placing the internal CI in the most challenging location (usually the geometric center of the densest area) provides the greatest assurance that sterilization conditions were achieved throughout the entire pack. If conditions are adequate at the most difficult point, they will be adequate at all easier-to-reach locations.
Question 6: What is the Bowie-Dick test used for?
- To test biological indicator viability
- To evaluate the air removal efficiency of pre-vacuum steam sterilizers, detecting air leaks, inadequate air removal, and steam penetration problems (Correct answer)
- To measure the concentration of EtO gas
- To test the drying capability of the sterilizer
Correct answer: To evaluate the air removal efficiency of pre-vacuum steam sterilizers, detecting air leaks, inadequate air removal, and steam penetration problems
The Bowie-Dick test is a Class 2 chemical indicator specifically designed to evaluate the air removal performance of dynamic air removal (pre-vacuum) steam sterilizers. Residual air pockets prevent steam from reaching instrument surfaces. The test uses a standardized test pack with a chemical indicator sheet that reveals non-uniform steam penetration patterns.
HSPA Biological and Chemical Indicators 2
What is the correct incubation time and temperature for steam sterilization biological indicators?