Biological Indicators

Biological indicators are generally accepted as the most suitable device to use for monitoring sterilization processes in steam, Ethylene Oxide & Dry heat, Gamma/E-beam, and H₂O₂/Plasma. The BI’s contain a specific microorganism used to assist in sterilization processes that render a product sterile in its final package or container. They are also used for the sterilization of equipment, materials, and packaging components utilized in aseptic processing. 

The indicators can be supplied as:

  • Spore Strips 

  • Spore Suspensions

  • Self-contained

  • Miscellaneous

BI’s are conventional spore growth readout indicators specifically designed for reliable monitoring of sterilization processes without the use of enzyme-based technology or specific and specialized incubators or monitoring devices. 

All BI’s comply with the performance requirements of ANSI/AAMI/ISO 11138-1 and the USP requirements. 

Incubation time depends on the type: strips and suspensions need to be incubated 7 days, self-contained BI's 24/48 hour, for steam a rapid 10-hour indicator is available.

 

Spore Strips

Biological spore strip indicators consist of bacterial spores injected onto a paper filter carrier or disc contained within a glassine envelope. For usage the spore strip is removed from the load and aseptically transferred into appropriate microbiological culture medium. Biochemical activity of the microorganism produces acid by-products that, when transferred to standard broth, will demonstrate noticeable turbidity and in the case of using a culture media with pH indicator, the culture media will have a noticeable color change. Turbidity or a visual pH color change indicate a sterilization process failure.

 

Spore Suspensions

 

Spore suspensions are biological indicators used for direct inoculating on or into units of the product to be sterilized. The microorganism is added to a liquid substance containing 20% ethanol.

Spore suspensions are used to inoculate products undergoing sterilization. They are available for sterilization processes using:

  • Steam

  • Ethylene Oxide

  • Dry heat

  • Gamma/E-beam

Spore suspensions are provided with population and resistance values to the sterilization process.

Each vial contains 10 ml of spore suspension in 20% ethanol.

 

Self-contained

Self-contained biological indicators are fast working reliable indicators for monitoring sterilization processes using: 

  • Steam, 

  • H₂O₂/Plasma 

  • Ethylene Oxide & Dry heat

These indicators consist of a self-contained unit that includes bacterial spores infused onto a paper filter carrier and a small glass ampoule containing a proprietary formulation of soybean casein digest culture media with a pH indicator encased in a plastic vial that serves as the culture tube. The pH indicator remains purple when there is no spore growth and yellow when there is spore growth. This allows quick visual determination of sterilization failures (yellow color).

Self-contained biological indicators are available on a paper carrier (Tyvek disc for H₂O₂/Plasma) plus a sealed glass ampoule within a vented plastic vial.

 

Miscellaneous

For the incubation of the NSC BI's, preset incubators are available. These incubators have 15 slots for placing the BI's and include a crushing well to enable the user to activate the BI's.

They are designed for incubating NSC biological indicators. These models are set on a temperature of 37°C (for E.O.)  or 60°C (for steam).

There are 15 incubation slots available to place the self-contained biological indicators with a crushing well to activate the BI’s.