Qualification of Sterilisation Processes

Elimination of microorganisms


The efficacy of any sterilization process will depend on the nature of the product, the extent and type of any contamination, and the conditions under which the final product has been prepared. All sterilisation processes need to be qualified and re-qualified.

We can offer:

  • Heat resistance determination of spores (D-value determination)
  • Microbiological qualification of sterilisation processes 
  • Qualification of depyrogenisation processes

When performing a microbiological qualification of a sterilisation process, spores with a known resistance to steam (D-value) are used. The most common test organism to use is Geobacillus stearothermophilus but other organisms, like Bacillus subtilis can be used. D-value refers to decimal reduction time and is the time required at a certain temperature to kill 90% of the organism being studied.

Biological Indicators (BI) are used to control the efficacy of the sterilisation method.  The indicators, for example strips, sand or solutions, are prepared with spores which have a high resistance to specific sterilisation processes like steam, dry heat or gas. For steam sterilisation, spores from Geobacillus stearothermophilus are used and for dry heat sterilisation the common organisms are  Bacillus subtilis or Bacillus atrophaeus. Cultivation of the BI-sample is done to control the elimination/reduction of spores during the sterilisation method that has been tested.