For many years now some of the end users of Biological Indicators have
been routinely sending out samples of BI’s (Biological Indicators) to Third Party
Laboratories for both D-Value and population verification. On an initial validation
or on an annual revalidation of Sterilization cycles, the cycles are challenged with
Biological Indicators to demonstrate actual microorganism lethality produced
during the sterilization a cycle. In order to present a cycle challenge, these
‘resistant microorganisms’ must be tough enough to meet specific standard
requirements as set out by AAMI, ISO or USP. For example, with Steam
Sterilization at 121C, AAMI, ISO and USP all state that if a BI is being used for a
Validation, the minimum acceptable D-Value or Resistance for that BI is 1.5
minutes.1 Thus the possible need for resistance verification prior to BI use.