You might consider adding SPS to your "flushings". R.Randolph
On Fri, 31 Mar 2000 23:09:04 +1000, "Paul A. Yeatman" <pauly at eisa.net>
>I am trying to validate a number of antibiotics using a 'bioburden test'.
>Due to the antimicrobial nature of the products being tested, I am having
>trouble getting our test organisms to grow.
>>The products are vancomycin and gentamycin. Out test organisms are Bacillus
>subtilis and Pseudomonas aeruginosa (at approx 100cfu/ml).
>>Ideally we would filter 50 mls of the product using either a 2 micron
>cellulose membrane, or a durapore membrane. So far I have tried flushing
>with sterile water WFI, followed by a regime of letting the membrane sit
>immersed in Tryptone Soya broth TSB for differeing amounts of time, in an
>affort to kick start the microbial growth.
>>As it stand, I am up to about a 6000ml WFI flush, followed by 3x 20mins of
>TEB (for a total of 2000ml TEB), which is getting rather excessive.
>>Does anyone know of a medium our media department can make that will
>deactivate the antimicrobial effects of these antibiotics, while allowing
>our t6est organisms to grow?
>>I have tried a method similar to what we have successfully used for a
>cytotoxic antimicrobial - 5500ml WFI followed by 3x 20min of TEB (1500ml
>total) with a cellulose membrane, filtering only 5ml of product, but to no
>effect (returns were around 25% of the controls for gentamycin, and worse
>>Any insight would be appecitated.