@sandyabbey. I believe "colonized" means that a person has spores in them even though they do not necessarily have active C.Diff. I believe the CDC website talks about this. I have had a back to back dose of vancomycin, and now test positive. That may be the lag in spores exiting or I may be colonized. Again (I believe) lots of people in U.S. have some spores in them but I should think "colonized" means more. I know i read somewhere that some people are colonized but never get C.Diff.