Answer:
Before the antibiotic, the ‘good’ bacteria had colonized her intestines and formed colonies that made up her biome. These colonies out-compete other bacteria, including ‘bad’ bacteria that tried to grow in the intestines hence protecting her intestines from infection.
However, the antibiotics wiped out the established colonies of ‘good’ bacteria –destroying her biome- and gave room for recolonization of the intestines by bacteria. The secondary succession gave a chance for the ‘bad’ bacteria to also thrive and cause her massive infections.
Valence is the number of electrons an atom must gain or lose in order to consummate its outer energy level or have a stable octet in its outer shell
I guess because of concentration.....it stops !
Because bacteria replicates so quickly we use it for our own purposes