And then we had 4. We discovered new ones, at one point I believe up to 7. But resistance made it go down pretty much by one per decade, but each next one ended faster. And then it hit zero, in 2012 I believe.
Now we may (maybe) be back up to one. Big whoop. Not going to last.
The problem is that evolution is out-researching us, the problem is that we're losing the war, not any particular battle. Antibiotics used to last 3-5 decades. Now we're down to years. While we do find new antibiotics on a regular basis, the problem is the speed of adaptation. The problem is that science is losing/has lost the "battle with darkness" as it was called 700 years ago. We are now in the situation that there are people dying because they entered hospitals for unrelated reasons (where they were exposed to these bacteria).
The problem is that we need to let millions of people die of curable diseases constantly or risk a Spanish flu like incident that can be reasonably expected to kill somewhere between 500 million and a billion humans today.