While this case shows a beautiful trophozoite 'unicorn' for national unicorn day, it has an atypically-large karyosome which makes it challenging to identify it as E. coli. I therefore added some additional trophozoite photos from this case. Note the smaller, eccentric karyosome and clearly clumped peripheral chromatin seen in the following trophs:
As Idzi pointed out, this one looks like a dog's head!
The cysts were clearly consistent with E. coli, containing >4 nuclei (8 in the mature cyst).