In that case, you get the infection, you're exposed to the bacteria, you're sick, and then you take, say, an antibiotic which cures it, and those drugs are actually working to kill the bacteria.
Neste segundo caso,  colles a infección, exposte á bacteria, enfermas, e despois tomas un antibiótico que a cura, e eses fármacos traballan para eliminar a bacteria.