Answer: No Strongyloides stercoralis or other larvae detected. A motile Bacillus sp. was present, accounting for the motility observed on the Strongyloides agar culture plate.
This was an unusual case because the bacteria produced an interesting motion which superficially resembled larval movement. However, the observed motility was not the expected sinuous movement of larvae through bacteria, but instead, consisted of regular and continuous clockwise or counterclockwise swirling within a confined region of the plate.
Multiple Gram stained preparations from these areas showed large Gram-variable to Gram positive rods with spores consistent with a Bacillus species. Smaller Gram negative bacilli (likely coliforms) were also seen in the background.
It's important to remember that things other than Strongyloides stercoralis larvae can demonstrate motility on Strongyloides agar cultures. In this case, the unusual motility pattern was due to fecal bacteria. However, we've also seen mites, hookworm larvae, and even larvae from free-living nematodes demonstrate visible motility. That is why we work up all positive cultures with microscopic identification of the motile objects.
Thanks for the great discussion on this one!