jchend

I have an unknown microbe, and I think it's Proteus vulgaris, but I'm not sure that the hydrogen sulfide test is positive. After performing the H2S test, I get a yellow butt, with NO black color along line of stab inoculation, but a dark precipitate at the TOP of the medium. What does that mean??? A black color along the stab or throughout the medium is supposed to be positive, and no black is negative. Well I'm stuck somewhere in the middle. Please help, I've looked everywhere for this type of result and can't figure out what it means.