Accutane is related chemically to Vitamin A, and being on it is similar to being on an overdose of Vit A, so it is very toxic to the liver. I was on it when I was a teenager and they took blood quite often to monitor liver values, triglycerides, etc. Taking oral steroids with accutane would be just stupid, and is asking for jaundice and/or liver tumors.
And taking anti biotics severely inhibits the affects of oral steroids. That's why women who take the pill have to be careful if they need to use anti biotics. Same goes for guys using oral steroids and wanting to run antibiotics. It will dull the affects substantially.