Are CFUs the same as AFUs?

No CFUs and AFUs are not comparable, although they cover some of the same microorganisms and show correlated results. This variance is due to the high analysis efficiency of Biofluorescent Particle Counters, which will detect particles with viable characteristics even when compendial methods may have failed to detect them due, for instance, to the particles having been damaged or lost by the collection method, or being otherwise non-culturable. Additionally, there’s the possibility that a small number of non-viable particles may possess fluorescence characteristics which cause them to be detected as viable particles; this can be reduced by testing possible ‘interferent’ materials and the management or elimination of their use in the controlled environment.

It would be required to run the BioTrak® alongside current methods during validation, for baseline determination and to demonstrate method equivalency as set out in the qualification testing procedure advised by TSI Inc.