C diff is frequently caused by antibiotics wiping out healthy gut flora allowing bad bacteria to take over. The antibiotics that commonly lead to c diff are clindamycin (for example, Cleocin), fluoroquinolones (for example, levofloxacin [Levaquin], ciprofloxacin [Cipro, Cirpo XR, Proquin XR]), penicillins, and. cephalosporins.