I got bit, now I'm getting billed!

In April, I was bitten by a resident. It broke the skin and bled, so I went to occupational health to get it fixed up. I didn't know if I should have blood drawn or not, so the nurse called my HR person, who said yes, get the labs done. So I did. Now, all this time later, I get a bill for $179. When I called the billing dept, they said workman's comp was denying my claim. Someone smart, help me out here.