*No* There are several reasons why this might not be true, as Alexander has discussed. An antibiotic often has a molecular target that isn't present in all bacteria, it's *extremely* hard to get antibiotics to certain parts of your body, and some bacteria will be defended against a antibiotic attack by biofilms, resistance mechanisms, and sheer statistical probability. That is not to say that many don't die. Indeed, one of the major causes of [*Clostridium difficile*][1] infection is that antibiotics kill most of your gut bacteria, allowing the somewhat better protected *C. diff* to proliferate, start producing toxins, and send you to the hospital with symptoms ranging from diarrhea to perforated colon and worse. That disease is a direct consequence of "Antibiotics kill some but not all bacteria in you". [1]: http://en.wikipedia.org/wiki/Clostridium_difficile ......