Staph live everywhere in every nook and cranny. Most are immune to most staph infections but a nose ring is in an area where there is moisture and constant air flow increasing the chance of infection and, if not clean, of developing into something more serious.
I have no idea what the attraction of a nose ring is... quite the turn off to me, but if you get one, keep it clean until the skin heals around it. Polysporin is good. Apply frequently until the skin heals.