We perform stopper sterilization validation by spiking x number of stoppers
with biological indicator suspension and, upon completion of steam
sterilization, we incubate the spiked stoppers in appropriate media at the
Our regulatory body, CVM, is requiring that we determine, via a recovery
method, the number of colony forming units spiked on the stoppers. This
suggests spiking stoppers as controls and attempting to quantitate the
number of colony forming units actually placed on the stopper (as CVM was
not satisfied that we routinely determined population verification on our BI
What is a realistic recovery expectation? If we spike 10E6, our worst
recoveries are about 10E4--average recoveries have been 10E5. These
recoveries seem low.
Can someone suggest a published reference on this situation and/or perhaps
suggest a possible recovery method? Is anyone else faced with this same
situation? If you only are consistently recovering 10E5 cfu, have you
increased your validation challenge to 10E7 in order to claim 10E6 kill
(seems so incredibly excessive to me).
Thanks for any insight you can provide.
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