We're talking about dry hopping with wet hops. You already said you have no experience with that.
Some part of the processing of commercial hops kills the microbes; I'm not entirely sure what. Indeed it's clear that dry hopping with commercial hops is not a big contamination risk, in contrast to fresh wet hops or any other plant materials.
If you do, make sure it's one that uses unprocessed wet hops on the cold side. Also ask about centrifuging or other methods that can remove or kill microbes.
Hops inhibit gram positive bacteria. More specifically, the isomerized alpha acids (and probably some other components) are bacteriostatic against these gram positives, which include but are not limited to lactic acid bacteria.
Hops do not inhibit:
- yeast
- mold
- gram negative bacteria
- gram positive bacteria that have built up a hop tolerance
... All of which will be found on the wet hops.
Cheers
Edit: whoops, polarity issue