"It's possibe that there were relatively fewer bacteria at that time,..."
All you need to start with is just one to be ankle deep in them in a few
days, if there was no death.
"...and that their multiplication rate was more restrained than at
present."
Possible because you wish it to be so, or because you have evidence that
that was the case? Just because an ugly fact like bacterial growth rates
contradict your utopian vision doesn't mean you can wish it away by
claiming, without evidence, that it might not be true.
Kevin L. O'Brien
klob@lamar.colostate.edu