HSPA Biological and Chemical Indicators Flashcards
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Read the first 6 HSPA Biological and Chemical Indicators flashcards as text
What is the primary purpose of a biological indicator (BI) in sterilization monitoring?
Answer: To confirm that the sterilization process was lethal to highly resistant bacterial spores, providing the highest level of sterility assurance
Biological indicators contain standardized populations of highly resistant bacterial spores that serve as the gold standard for verifying sterilization lethality. A negative result (no spore growth after incubation) demonstrates that conditions inside the sterilizer were sufficient to kill even the most resistant organisms, providing the highest assurance of sterility.
Which organism is used as the biological indicator for steam sterilization?
Answer: Geobacillus stearothermophilus
Geobacillus stearothermophilus spores are used for steam sterilization because they are among the most resistant organisms to moist heat. Their high resistance to steam sterilization conditions makes them an appropriate challenge organism. If the sterilization process kills G. stearothermophilus spores, it will have killed all less resistant organisms.
Which organism is used as the biological indicator for ethylene oxide (EtO) sterilization?
Answer: Bacillus atrophaeus (formerly B. subtilis var. niger)
Bacillus atrophaeus spores are used for EtO sterilization monitoring because they exhibit high resistance to ethylene oxide gas. Each sterilization modality uses a different challenge organism that is specifically resistant to that method's killing mechanism. This ensures the BI provides a valid challenge for the specific sterilization process.
What is a Class 5 integrating chemical indicator?
Answer: An internal indicator that responds to all critical parameters of the sterilization cycle and correlates with biological indicator results at stated sterilization conditions
Class 5 integrating indicators are designed to react to all critical parameters of the sterilization process (time, temperature, and steam presence for steam sterilization) and their performance correlates with biological indicator kill at stated sterilization values. They provide the highest level of chemical indicator assurance, second only to biological indicators.
What is the difference between a Class 1 and a Class 4 chemical indicator?
Answer: Class 1 (process indicator) only distinguishes processed from unprocessed items, while Class 4 (multi-variable indicator) reacts to two or more critical sterilization parameters
Class 1 indicators (like autoclave tape) simply show that an item was exposed to a sterilization process, helping prevent mix-ups between processed and unprocessed items. Class 4 multi-variable indicators react to two or more critical sterilization parameters, providing more specific information about whether adequate conditions were achieved.
How often should biological indicators be used to monitor steam sterilizers?
Answer: At least weekly, and with every load containing implantable devices
AAMI ST79 recommends biological indicator testing at least weekly for routine loads and with every load containing implantable devices. Some facilities test every load for maximum assurance. For implants, BI results should be confirmed negative before the implants are released for patient use, unless there is a documented urgent clinical need.