My husband has struggled with c-diff. In general, people with IBD are more susceptible to c-diff - it is usually people with IBD who get c-diff infections even without the use of antibiotics, because there is already an imbalance in the flora of the gut of people with IBD. Also, people with IBD have higher recurrance rates of c-diff infection, ie. you take antibiotics to fight off the active infection, and 2 weeks later it's back.
Also, my husband's infectious disease doc believes that any kind of immune suppression can increase the rate of relapse. So, for sure, imuran can be one of the reasons you keep relapsing. However, there are plenty of normal people who struggle with relapses even though they are not on any immune suppression.
If you haven't been able to get rid of it with 2 week of antibiotic therapy, some doctors try a slow taper of the antibiotics, for eg. you go from antibitocs 3 times a day, to twice a day for 2 weeks, and then, once a day, etc. Some try the pulse method - where you take the antibitocs 3 times a day for 6 days a week, then 3 times a day for 5 days a week, etc. Both methods are believed to help kill the c-diff spores as they become bacteria, bettering your chances for a full recovery.
Talk to your doc about options. Also, there is a new antibiotic around the corner called fidaxomicin that is more narrowly targetted towards c-difff that has slightly lower rates of recurrance than vancomycin and flagyl. Also, there is a yeast called saccromyces boullardi, marketed as florastor, that is supposed to help fight c-diff. My husband takes 3 of them a day, 2 packets of vsl and 2 cups of home made yogurt every day to try to keep the c-diff monster at bay.
Good luck, I hope you beat it back soon.
Husband with Crohn's
Diagnosed March 2003 Ulcerative Proctitis
Diagnosed March 2008 Crohn's & C-diff, hospitalized 45 days
Crohn's in Remission since June 2008
C-diff recurrence Sep 2009
Reactive Arthritis Nov 2009
Currently c-diff free
Osteopenia of spine (Mar 2010)
Canasa (1gm), Lialda (4.8 gms), Remicade (8 weeks)
Currently In Remission