Rat bite!

One of my foster kittens was bitten by one of my pet rats yesterday! I'm not sure if there is anything special I should do to treat it...
She put her tail tip too close to the cage and one of the rats managed to grab it and wouldn't let go! I had to actually pull her tail away, and it bled a lot. I stopped the bleeding and cleaned it up really well and then put antibiotic ointment on it. I can't really see how deep it is because the fur is too thick there. She is already on antibiotics because of a problem with her spay incision (it partially opened about a week after the spay).

Keep the wound open. That means no antibiotic ointment (she's probably already licked it off anyway.) If you can keep her from licking it (good luck) that would help. On the good side, she's on antibiotics, so it probably won't give her rat bite fever or anything like that. Just watch it for an abcess or if she's still treating it funny in a couple day.

Poor kitty. Been there, done that, have the scars to prove it.

Just keep it open and watch that it doesn't get infected.
I think most rat owners have been through this.