Answer:
The bacteria might have gotten immune to the hand sanitizer.
Step-by-step explanation:
While the hand sanitizer kills the bacteria, the bacteria starts to learn how it works and how to react when it needs to go up against it. Think of it this way, the hand sanitizer goes to the bacteria and starts to slap it to kill it, but while it is doing that, the bacteria starts to learn how it works and all of its moves. It then uses it moves against it and becomes a SUPER BACTERIA!!!
I really hop this helped, BYE