A sterilization biological indicator is a specialized live microbial product used to verify the performance of sterilization equipment, validate sterilization procedures, and monitor sterilization effectiveness in production processes. It is defined as a carrier inoculated with specific microorganisms that exhibit known resistance to a particular sterilization method, enclosed within internal packaging for controlled use.

By Structure: Strip Biological Indicators: Require both positive and negative controls for validation. Self-Contained Biological Indicators: Require only a positive control, simplifying the process. By ISO 11138-1 (2006) Classification: Biological indicators are categorized based on the sterilization method they monitor: Ethylene Oxide (EO) Sterilization Biological Indicators Moist Heat Sterilization Biological Indicators Dry Heat Sterilization Biological Indicators Low-Temperature Hydrogen Peroxide Plasma Sterilization Biological Indicators Formaldehyde Sterilization Biological Indicators By Incubation Time: Standard Biological Indicators: Detect changes in pH levels caused by microbial metabolism after spore recovery. Utilize acid-base indicators for color change interpretation. Require 24 to 48 hours or more for results. Rapid Biological Indicators: Detect enzymatic activity via fluorescence after spore recovery. Provide results within 3-4 hours. Advanced rapid biological indicators are currently in development internationally, with potential for results in under 1 hour.

In sterilization process validation, while certain parameters can be used to evaluate sterilization effectiveness, the degree of spore inactivation in biological indicators serves as the most direct measure of a sterilization program's efficacy. Biological indicators can be: Commercially available standard biological indicators, or Custom-prepared spores from the most resistant microorganisms isolated through routine production contamination monitoring.