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General Microbiology Testing

Biological Indicator Testing - BI Testing

The robust and repeatable biological indicator testing procedures utilised at Wickham Micro are aimed at confining the certified population of spores on manufacturer’s biological indicators (BIs) using an extraction, heat shock and plate count method.  Our techniques have been developed over many years of working with end users and BI manufacturers alike.

The requirements and performance specifications of biological indicators (BIs) used to verify sterilisation or decontamination processes are set out in ISO 11138 series (Sterilization of Healthcare Products – Biological Indicators).  These processes include, but are not limited to, moist heat, dry heat, ethylene oxide sterilisation, low temperature steam and hydrogen peroxide vapour decontamination.  BIs consist of a standardised and homogenous population of bacterial spores that vary in type or number, depending on the sterilisation or contamination method in question, but are typically a 6-log population of Geobacillus stearothermophilus and Bacillus atrophaeus, with known resistance to the mode of sterilisation being monitored, (so called D-value).

We perform all of the standard methods of biological indicator testing, with many BI types including paper strips, stainless steel discs and a variety of self-contained BIs.  Our technicians have also assisted with bespoke BI production and enumeration projects, in order to determine susceptibility of a wide variety of microorganisms to decontamination processes as part of proof of concept work, publications and end product manufacturer claims.  An example of this is our recent involvement in the publication of a joint study.

We can also assist you with BI troubleshooting along with purchasing and supplying the BIs and any other media required for testing, whether conducted by ourselves on your behalf, or for in-house routine use. We routinely offer validation and commissioning studies using BIs, particularly on autoclaves.  All biological indicators supplied and used in testing will be enumerated prior to conducting testing, to ensure suitability for use.

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