Corrections:
1) and, THUS, germs
2) second, it doesnt strengthen the RESISTANCE OF bacteria.
It kills the weaker/more susceptible bacteria, thereby leaving the stronger/less susceptible ones.
I always considered the word germs to be a catch-all for the various pathogens out there, be they bacteria, or virii.
Dictionary:
3. germ (n.)
a minute life form (especially a disease-causing bacterium); the term is not in technical use