Biological Indicator-Sterility Testing

What Are Biological Indicators (BIs)?

Biological Indicators (BIs) are test systems that contain viable microorganisms, providing a clarified resistance to a specific sterilization process. For a given sterilization process, whether necessary conditions were satisfied to destroy a certain number of microorganisms or not. This information can be provided by BIs, and This information also provides a high level of sterility assurance for the sterilization process. BIs can be used to monitor the efficacy of various sterilization processes. BIs can provide a direct evaluation of the process fatality, subsequently, the use of BIs to keep track of sterilizers can provide assurance in the efficacy of the sterilization process.

What is Biological Indicator Sterility Testing?

Generally, after completion of a sterilization load, performing the BI Sterility test on exposed BIs. The test is a qualitative test to yield results of either growth or no growth of the appropriate indicator organism.

BIs are typically used within process challenge devices that are designed to represent the most challenging products routinely processed. Endospores, or bacterial spores, are the microorganisms primarily used in BIs as they are considered to be some of the toughest ones to kill. Additionally, bacterial spores are chosen for a specific sterilization process built upon their known resistance to the specific sterilization process.

BI Sterility Testing Procedure

In the Biological Indicator Sterility test, a biological indicator is made up of a carrier material, on which bacterial spores with a defined resistance to the sterilization process have been applied. The general procedure for BI Sterility testing is placing BIs into soybean casein digest broth sterilely; subjecting to the growth requirements of the indicator organism, Incubating for a specific period of time and a certain temperature, and then determining whether any spores survived in the process. The samples are typically incubated for 7 days at 30°C for Bacillus atrophaeus in dry heat processes or 60°C for Geobacillus stearothermophilus in steam or vaporized hydrogen peroxide processes. The test will pass If no spores survive or grow, while the test will fail if we detect growth.

Applicable Standards

BIs testing and sample requirements are outlined in numerous standards including USP <55>, the ANSI/AMMI/ISO 11138 series parts 1-4, ANSI/AAMI/ISO 14161, and ANSI/AAMI/ISO 11135.

STEMart offers Biological Indicator (BI) Sterility Testing service for both traditional BIs and self-contained BIs, following the guidance in various standards. We can help you to perform this test whether during validation or during routine production as a lot release test.

If you have additional questions about Biological Indicator (BI) Sterility Testing or would like to find out more about our services, please feel free to contact us.