Membrane filters have been used suc

Membrane filters have been used successfully for many years to remove yeast,
bacteria and particulate from fluid streams. The ultimate integrity test for a
sterilizing grade membrane filter is the bacterial challenge. Unfortunately this is a
destructive test; the filter cannot be used afterwards to filter a product. As a
result, one of the most important aspects of the use of filters to remove bacteria
is to have a non-destructive integrity test, which is correlated to the production of
effluent in a bacterial challenge test. It is this correlation, rather than the non-
destructive integrity test alone, that provides assurance that the filter will perform
as intended. During production of sterile product, the filter should be subjected to
such an integrity test before and after filtration. This is done to ensure that the
filter meets specification, is properly installed and intact during filtration, and to
confirm the rating of the filter.