How are antibiotics used in the treatment of bacterial infections?
They are adminstered either as pills, injections, or applied to the the surface of the body (if the infection is external). Antibiotics release chemicals which either kill the invading bacteria or prevent them from multiplying by cell division. http://en.wikipedia.org/wiki/Antibiotics For most infections a course of antibiotics will last for 2-3 weeks. Antibiotics may also be prescribed as a preventitive measure, during a viral infection or recovery from injury. One problem with antibiotics is that they will often also kill helpful bacteria, such as those in the gut. Which is why they often cause stomach upset and the runs.
