Answers to your questions:
1. Depends on what you mean by volume. We typically direct transfer less than 1 g of product per medium bottle. For reconstituted product we usually transfer 1 to 2 ml. Regarding the number of samples, we have tested up to 100 samples per medium (for a dose verification).
2. Single solid dose (or reconstituted sample) per 200 mL of medium.
3. 100 mg of sample to 200 mL of medium.
4. Clean room.
Robert F. Guardino
Associate Director Microbiology
2320 Scientific Park Drive
Wilmington, NC 28405
Phone: (910) 254-7635
Fax: (910) 254-7416
e-mail: [log in to unmask]
We have been looking at different "alternate technologies" to assist
with steriity testing by membrane filtration. I am also getting
interested in looking at some that would be useful for direct transfer
testing. Obviously I would like to spend time on technologies that
others have found useful and are supporting in their respective
A question for the group - actually several questions - about
sterility testing by direct transfer:
1. What is the largest volume that you handle in sterility testing by
2. What is the normal ratio of sample to recovery medium used?
3. What is the smallest ratio (sample/recovery media) that you have
had to use to get adequate B/F results?
4. Do you perform direct transfer testing in an isolation chamber or
a clean room?
5. What "rapid methods" or "alternate technologies" have you looked
at for direct transfer testing, if any?
Thanks for the help.
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