The Bulls took an early 12-0 lead within six minutes but from thereon in the tables turned in the Catalans' favour.
The Dragons responded with three tries to take the lead, but a Jarrod hat-trick ensured that the Bulls remained in the contest, going into half-time 20-22 down.
Catalans ran riot early in the second half, scoring four tries in 25 minutes.
At 44-20, the Bulls responded with Sammut's fourth try of the match but it was too late as a third Clint Greenshields try ensured a 50-26 victor for the Dragons.
The result means that the Bulls will now miss out on a playoff place.