Huffpost article:
"Germs can and most likely do live on all bars of soap, but it’s very unlikely they will make you sick or cause a skin infection. Generally, those with a compromised immune system are really the only ones who should be extra cautious and stick to liquid soap. If you are healthy, your body will have no problem fending off the germs.
Bacteria lives quite happily in the “slime” of bar soap, but doing a few simple things (which you probably do already) will make it so the germs are of no consequence to you. Rinse off the bar in running water before lathering up to wash away the germy goop. And always store soap out of water (i.e. not in a wet bathtub), allowing it to dry between uses. That way, there’s no moist environment for germs to flock to in the first place.
If you’re just sharing the bar with family members, you have nothing to worry about since you probably share many of the same microorganisms anyway. Public bathrooms usually don’t have bar soap, but if you find yourself in that situation and have no other way to clean your hands after using the restroom, rinse off the bar, and then just make sure to wash your hands well — 20-30 seconds, both sides, under your nails, up to your wrists, like you learned in grade school. If you’re washing for long enough, the germs originally sitting on the bar will most likely wash off, too"