San Giovanni hospital declined to give details Saturday about the condition of the victim, whom authorities have not named but said is around 20.
The roommate, a fellow student at John Cabot University, is in police custody as they probe the attack early Thursday. Police have said the attack followed a night of alcohol and possible drug use.
John Cabot's president, Franco Pavoncello, in a message on the university's web site, said press or social media "rumors" do not accurately reflect what happened, but offered no details.
He urged prayers for the families of the victim and alleged assailant.