

What do you mean by strictly speaking? Germ theory was proven by Pasteur experiments in the 19th century and confirmed by countless of scientists throughout the 20th Century to this day. What more proof do you want when you can literally see bacteria expand and colonize a medium?
Please explain further. As of today when someone has a bacterial infection you have a direct evidence of it, you use an antibiotic, you kill the bacteria, you cure the illness. No miasmia, humors or worms involved. It’s like you are saying we have a space photo for a round earth but what if a discovery undo it tomorrow.