By Nancy Chobin, RN, AAS, ACSP, CSPM, CFER
Q: We have always run the biological test (BI) in the morning immediately after the Bowie-Dick test to make sure we do not forget to perform the test. We run the test pack by itself. We recently had a survey and were cited because we did not run the biological test in the first working load. We have done the BI test this way for years and no one has ever said it was wrong. What is the recommended process?
A: I always cite the Association for the Advancement of Medical Instrumentation (AAMI)’s documents since these are national standards. The Joint Commission and the Centers for Medicare and Medicaid Services (CMS) use these documents as a reference. The “Bible” for decontamination, packaging, steam sterilization and sterile storage is AAMI’s Comprehensive Guide to Steam Sterilization and Sterility Assurance in Healthcare Facilities (ST-79), 2013. Every facility performing steam sterilization should have the most recent copy to ensure their policies, procedures and practices confirm to AAMI’s national standards. For the purposes of your question, I will only discuss biological testing of wrapped cycles (not immediate use cycles).
AAMI states, “Biological indicators provide the only direct measure of the lethality of the sterilization process.” Therefore, biological testing is an important part of the overall quality assurance testing sterilizers. Due to the importance of this testing, it is vital that the test be performed correctly so the test results provide the desired information.
BIs should be used within a test pack, now called a process challenge device (PCD). There are a number of times your sterilizer should be tested. These include:
- Routine sterilizer efficacy testing which should be performed weekly, preferably each day the sterilizer is used.
- All loads that contain implantable devices (devices that are implanted in the OR and remain in the patient for at least 30 days
- Sterilizer qualification testing after new sterilizer installation, relocation of a sterilizer or after a major repair.
PCDs can be purchased pre-made from outside manufacturers or made within the facility. AAMI provides guidance on how to construct a PCD if needed. However, due to the potential inconsistencies that can result when self-made, most facilities purchase pre-manufactured PCDs.
Always read the manufacturer’s instructions for use (IFU) regarding which cycles and temperatures the PCD has been validated for. Store the PCDs according to the recommendations of the manufacturer.
When performing BI testing, it is important to perform the test correctly to ensure that the test results will provide accurate information about the selected sterilization cycle. Biological monitoring is intended to verify that the sterilization conditions within the load were adequate to kill a known number of bacterial spores. As previously stated, biological monitoring is the only way to measure the lethality of a sterilization process. Bacterial spores are microorganisms that are highly resistant to being killed. Sterilizer manufacturers validate their sterilization cycles using biological indicators containing bacterial spores. For this reason, routine sterilizer efficacy monitoring in healthcare facilities should also be con-ducted using BIs. The spore that is the most resistant to the steam sterilization process is Geobacillus stearothermophilus.
There should be a policy and procedure for biological testing of sterilization methods in used within the facility. Sterile processing staff should be in-serviced in the process initially and competencies verified initially and annually thereafter. Just placing a PCD inside the sterilizer is not good enough; the test must be performed the same way every time.
Test Procedures for Routine Biological Monitoring of Sterilizers Larger Than 2 Cubic Feet: (Non-Tabletop)
• The BI PCD for routine sterilizer efficacy testing should first be checked for its expiration date.
• Affix a lot control label to the outside of the PCD to identify the sterilizer being tested (especially in facilities with more than one sterilizer and text packs could get mixed up unless labeled).
• The test pack should be placed flat, facing up, in the area of the sterilizer least favorable to sterilization (i.e., the area that represents the greatest challenge to the PCD). For non-tabletop sterilizers, this area is usually on the bottom shelf of the sterilizer cart over the drain line. However, the sterilizer manufacturer should identify in the IFU the exact location for the BI PCD, and SPD personnel must comply with the manufacturer’s instructions.
• To ensure correct placement of the BI PCD, SPD personnel should place the BI PCD on the sterilizer cart first, then load the other items for sterilization. For smaller sterilizers, carts are not usually available; the test pack should be placed on the bottom rack over the drain line, and then other items should be loaded into the sterilizer.
• The test should be run in a fully loaded chamber to present the greatest challenge to the sterilization process.
• After exposure to the sterilization process, the PCD should be allowed to cool for the length of time specified by the manufacturer.
• The BI vial is then removed from the PCD and labeled with the sterilizer number, cycle number, and date in the space provided on the vial (do not affix lot labels to the vial).
For tabletop sterilizers, (AAMI defines a tabletop sterilizer as one with a chamber size of 2 cubic feet or less) the location of the test pack can vary with the tabletop manufacturer but generally the location is on the bottom shelf near the door. Therefore, the placement and location of the test pack in the load is important. I always recommend that the test pack be placed on the autoclave cart (or inside the sterilizer for sterilizers without carts); FIRST, since the placement of the test pack is critical to the test results.
For qualification testing in non-tabletop sterilizers, the testing is performed in empty sterilizers. However for tabletop sterilizers, all biological testing, including qualification testing is always performed in a full load.
All biological testing should be accurately documented in a log book or other method, and include the following:
• Date and time BI placed in autoreader/incubator
• The sterilizer number or other method of identification
• The cycle or load number
• The lot number of the BI vial
• The name of the technician placing the BI in the autoreader/incubator
• The date and time a control vial was placed in the autoreader/incubator
• The lot number of the control vial
• The date and time the BI was read/discarded
• The result of the BI vial
• The technician who read the BI results
• The date and time the control vial was read/discarded
• The result of the control vial
• The technician who read the control vial results
To ensure that information is not omitted, a review of the BI records should be performed each day by reviewing the entries from the previous day to ensure all information was documented.
Biological testing is an important part of the sterile processing technician’s roles and responsibilities. Due to the importance of BI testing, sterile processing personnel must make sure the test is performed correctly by checking the BI manufacturer’s instructions for use including, storing, performing and using the test correctly. Careful and complete documentation of all BI testing is required. Any sterilization records can be subpoenaed in a court of law. Therefore, it is important that the testing meet the standards set by AAMI and the results documented.
Nancy Chobin, RN, AAS, ACSP, CSPM, CFER, is a sterile processing consultant and educator.
Reference: Association for the Advancement of Medical Instrumentation. Comprehensive Guide to Steam Sterilization and Sterility Assurance in Health Care Facilities, (ST-79), 2013. Sections 10.6.1; 10.5.3.2