Is prostatitis usually treated with antibiotics?

Yes. The mainstay of treatment is antibiotics for several weeks and anti-inflmmatory medications such as advil, tylenol, (acetaminophen) or motrin.
It depends. There are different kinds of prostatitis. Types I and ii prostatitis are treated with antibiotics for at least 4 weeks. However type iii prostatitis may not repond to antibiotics, so other treatments should be used if symptoms persist after a course of antibiotics and there is no evdience of bacteria in the urine.