Poison ivy is a plant that causes a topical rash, antibiotics can't help in any way with this. Maybe you've mistyped something?
When skin barrier gets broken like this, you are now vulnerable to bacterial infection.
I can't believe someone gave you anti biotics for poison ivy.
At this point I genuinely consider the medical system about as bad as the service department at a car dealership. They'll sell you anything technically legal just to keep their stats high.
No, the service department has a bad reputation for a reason. They tried to tell me a wiper blade would cost me USD 80 with a straight face. Not even the whole set, a single wiper blade. It costs under USD 15 anywhere else other than the dealership.
My guess is they are counting on people not looking at the itemized bill.