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
for vancomycin).
Any insight would be appecitated.
