"Running out" is a bit of a weird title here, it doesn't mean that some deposit is running dry. There are more and more bacteria getting resistant for more and more types of antibiotics, making them no longer effective. Even a bottomless supply of antibiotics is useless if it doesn't actually kill the things it's supposed to kill.
I suppose the "running out" part would mean that there are only so many types of antibiotics, if none of them are effective anymore (or not enough of them are effective enough) we would be in some deep shit.
(being in deep shit may cause a severe risk of bacterial infection, I highly recommend not being in such a situation)
It's implying suicide