Bacteriophage (phage for short) use bacteria as a womb. They inject their DNA into the bacteria. They take energy from the bacteria and make 50 or more phages within the bacteria. Then they break open the bacteria and the phages go on there way.Depending on the type of phage this takes about twenty minutes.
There are two advantages to this One, the phages grow faster than the bacteria so they can over take them. Second, the phages end up in the same area as the infection.
One thing bacteria do is to form which are clumps of bacteria. The have small holes running through the film so that the bacteria in the middle can get food. It is 100 times harder for antibiotics to kill of a biofilm than it is to kill off individual bacteria.. Antibiotics kill of the outer layers of bacteria, but they grow back out from the middle.
Bacteriophage on the other hand can kill off the bacteria in the biofilm because there are more phages born every 20 minutes Check out my campaign to start a nonprofit to promote bacteriophage as a cure.
I will write something about phage therapy every day this month untill the campaign is over.