I think Dr S'avage is the glove handed killer. The nurses just make no sense and Celine and Kim aren't really strong enough characters yet, but S'avage doesn't have any prescense outside of the hospital and I think if they revealed it to be him, he'd leave and it'd be the end of this hospital business they're focusing on right now. (Like in the past when they've had freshers and college kids and when those stories are finished, they just kill everyone and focus on another setting in the village).
That's just my guess, unless they just bring in a total randomer or someone unrelated to the hospital. It'll end up being Patrick or Sienna, it IS hollyoaks ahaha