Biological indicators for sterilization

Biological Indicators: Their Importance in Sterilization Processes

Biological indicators (BIs) are valuable tools for monitoring sterilization processes and ensuring that no microbial colonization is possible on medical equipment or supplies. This article will discuss biological indicators- what they are, how they work, and their relevance in sterilization processes.

Definition

A biological indicator is the culture of live microorganisms that we use to monitor the effectiveness of sterilization processes. BIs work by providing a challenge to the sterilization process, and the results allow for proper assessment of the sterilizer’s effectiveness.

Types

There are many types of biological indicators such as bacterial and fungal.

• Bacillus Atrophaeus- non-pathogenic bacterial spores highly resistant to standard sterilization processes. We use them to assess the efficacy of sterilization in autoclaves, dry heat, and ethylene oxide gas.
• Bacillus Stearothermophilus- bacterial spores that are highly resistant to harsher sterilization methods like steam and dry heat. We user them for sterilization processes in the pharmaceutical industry.
• Geobacillus stearothermophilus- bacteria used to monitor the effectiveness of sterilization by radiation and gamma rays.
• Aspergillus Niger- fungal spores used to test bio-decontamination systems in cleanrooms and sterilization process efficacy by ethylene oxide gas.

How Biological Indicators Work

However biological indicators contain a known population of live microorganisms that will provide evidence for us to determine whether the sterilization process eliminates all microorganisms. If the sterilization process is successful, the BI’s microbial growth will not occur, and the results will indicate that the sterilization has been effective.

In sterilization processes, BIs have a pivotal role in ensuring that all microorganisms are destroyed. Every biological indicator carries a highly resistant organism in a controlled environment with a set population. These organisms are the most resistant strains known and will undoubtedly pass unscathed through the harsh environments used in sterilization. Biological indicators therefore serve as a useful tool in validating the sterilization process’s effectiveness.

Applications of Biological Indicators in Sterilization Processes

We use them for sterilization methods such as gamma irradiation, ethylene oxide, peracetic acid, and steam. These sterilization processes require routine validation to ensure that they are correctly operating and are safe for patients. A well-characterized biological indicator provides valuable information about the sterilizer’s effectiveness, which helps to maintain high standards in patient safety.