You may be testing wrong; did you test stool taken on three consecutive days; this is the best way to test for Fragilis; because like Blasto, Fragilis shed every other day; if you just one stool, it will not be there.
Have them test your stool three days in a row; it must be the first stool sample of the day; not the second; this is the advise of the dr. at Jetti Katz; that is how he found my Blasto, which other labs did not find, after I had taken Metronidazole before; they thought it was gone; sure enough, they found Blasto on the second and the stool sample;
SO have them test three stool sample, taken on three days in a row; it must be the first stool sample of the day.