There's no good way to tell a pair of cute nurses that the antibiotic cream they probably saw in your bathroom while they were visiting to watch The Lion King in 3D is for the moles you had removed two weeks ago, and not treatment for some sort of weird rash or something equally icky and potentially transmittable.
There's the chance that they didn't notice anyway, but the odds of that are pretty low. That tube could not have been more front and center, and you noticed far too late. On the one hand, they're nurses, so they're probably fully aware of the myriad uses for antibiotic cream. On the other hand, they're probably also aware of uses which involve horrifying diseases that you don't even know about. And bringing it up later, say, in some sort of offhand and charming tweet, well, thou doth protest too much.
Oh, and it doesn't help that the name of the stuff sounds like the answer to the question "how do you get a venereal disease?"