It's pretty clear in the various series and movies that when Starfleet personnel use the term "lifeforms" they are specifically referring to intelligent life, and not life in general. So I think when McCoy spoke of "life" he was referring to sapient people, and not simply anything alive.Archer doesn't wash his hands? gross.
Not clear enough for me.
From Voyager Episode "Infinite Regress"
NAOMI: How about the suborders of the Prime Directive? I know all forty seven of them.
depositing new lifeforms on a planet may be violating one of those 47 suborders of the prime directive
TNG "A Matter of Time"
PICARD: Of course, you know of the Prime Directive, which tells us that we have no right to interfere with the natural evolution of alien worlds. Now I have sworn to uphold it, but nevertheless I have disregarded that directive on more than one occasion because I thought it was the right thing to do. Now, if you are holding on to some temporal equivalent of that directive, then isn't it possible that you have an occasion here to make an exception, to help me to choose, because it's the right thing to do?
if altering the natural evolution of worlds is a violation of the prime directive, introducing new species to an ecosystem could cause sufficient alteration of the natural evolution of life on that planet.
TNG "Homesoil"
PICARD: Doctor Crusher is still making her determination. Mister Mandl, you know the Prime Directive.
MANDL: Are you saying that I knowingly defied it?
PICARD: That's what I have to find out. You're a man obsessed with what you do. Who knows what an obsessed man will do to keep going? Kill, perhaps?
MANDL: I create life. I don't take it.
Picard accused Mandl of violating the prime directive before he found out that the life they were investigating was intelligent life.