help identify this enterobacteriaceae

[Gregory D. Rose]

I am stuck.  Trying to identify my unknown in medical microbiology
class.  Have it narrowed to maybe.. thats MAYBE two organisms:  E. coli
and Proteus Vulgaris.  My results have not been overly convincing
however.  Here goes.

Medium sized gray colonies with white center, alpha hemolytic on BAP
It ferments lactose (purple colonies with green sheen on EMB)
TSI was acid/acid no gas, no H2S produced
SIM was + + +  (very positive for H2S here but negative on TSI)
Urease negative
Pdase negative
Citrate negative
Lysine negative
Ornithine negative
IMViC - + - -

Help...  please.

respond by e-mail if possible to:  gdrose at exploremaine.com
Thank you