Once Again, Untested Assumptions: Microbiota, Probiotics and Patient Harm

This article is a fresh reminder of an untested assumption, something not uncommon in medicine.

Probiotics, to restore the microflora and prevent antibiotic associated diarrhea and Clostridium difficile infections, how could these be unsafe?

Probiotics are presumed low risk but we simply don't know the potential harms because adverse events are not rigorously assessed in related clinical trials.

Now when asked about the safety of probiotics,  I am obligated to modify my answer: 

Probiotics are likely safe but we simply don't know for sure.