What are the advantages of antibiotics?I need a very detailed explanation of antibiotics' advantages, for the sake of my school extended essay....

Antibiotics are substances are obtained from bacteria and
fungi. Antibiotics are used for many different purposes. The most important of these
uses is as drugs to fight various diseases caused by harmful microorganisms. use of
antibiotics has now made it possible to treat many diseases that were fatal prior to
development of antibiotics. A few are used to treat certain
cancers.

Antibiotics cure diseases by their property of
being selectively toxic to microorganisms. When administered to a patient, they damage
certain types of cells in the patient's body, but do not damage others.  Antibiotics
used as medicines are harmful to the cells of disease-causing microorganisms, but not
normally not harmful for the normal body cells. Such antibiotics are used to treat a
variety of bacterial diseases.  A small number of antibiotics, have also been developed
to  attack human cells for treatment of cancer.  They are able to cure cancer by only
damaging cells that are in the process of
dividing.

Antibiotics are also used to treat infectious
diseases in animals and to control bacteria and fungi that damage fruit and grain. 
Sometimes small amounts of antibiotics are added to livestock feed to stimulate the
animals' growth.  Small quantities of antibiotics are also used as food
preservatives.