Actually, recent studies have stated that there is a high correlation between users that use Accutane and users that took tetracycline antibiotics for acne...so many speculate that its the antibiotics not the accutane that can lead to UC.
Potential Association Between the Oral Tetracycline Class of Antimicrobials Used to Treat Acne and Inflammatory Bowel Disease
http://www.nature.com/ajg/journal/vaop/ncurrent/full/ajg2010303a.html
article said...
Previous studies have shown an association between isotretinoin and inflammatory bowel disease (IBD). The majority of patients prescribed isotretinoin for their acne are previously on an extended course of antibiotics. Therefore, it is important to consider antibiotic use as a confounding variable for the development of IBD.