There are two schools of thought on this question.  One says most fungi will be exposed during a two-week sterility test.  While that may be correct, the operative word is MOST fungi.  The other school of thought is that to be absolutely sure, one should perform a separate fungal test concurrently with the sterility test.  The reasoning is that microorganisms prefer a soy based broth in which to grow, while fungi prefer a starcher environment such as a potato dextrose base.

We had a situation in our lab which proves the point.  A client sent in a sample for sterility and fungal testing.  The sterility test passed.  The fungal test did not demonstrate growth until several days after the sterility test was completed.  The tests were repeated using different media lot numbers and the results were the same.  Had a separate fungal test not been run, the standard sterility test would not have picked up on the fungal growth.  When CSP’s are to be invasively introduced into a body, due vigilance must be the operative word.