An antibiotic, is defined to be a drug produced by certain microbes. Most doctors use antibiotics to help fight the germs in a patient. Antibiotics are obtained from plants, fungi, air, water, soil, just about anything on earth. Antibiotics kill and attack the germ or virus in the body, but do not hurt the human cells, ordinarily. The antibiotics are used to treat many various types of diseases, such as tuberculosis, syphilis, and several kinds of infections.
People have been using antibiotics for more than 2,500 years. They used molds to help cure some skin infections and rashes. It was in the late 1800's that the real study of medicine began. Louis Pasteur discovered that bacterium was the cause of disease, and proved wrong the theory of spontaneous generation. After him there was Robert Koch, who developed a method of isolating and growing bacteria. Scientists tried developing drugs that could kill microbes, but they proved to be either dangerous or ineffective.
In 1928 there was a discovery by Alexander Fleming. He detected that a substance he called 'penicillin' destroyed bacteria. Then in the late 1930's, two British scientists invented a method of extracting penicillin from the mold. This was the start of developing new drugs to treat diseases and bacteria.
Over the years, numerous thousands of antibiotic material have been found in nature as well as produced chemically but, there are few that are safe and useful. However the ones that are safe and effective have saved many lives and have helped extend life expectancy.
Right now, there is more than 70 different kinds of antibiotics in use. Most antibiotics are used to treat infections, some for fungi and protozoa, but antibiotics are not usually effective against viruses. So they have developed other methods such as vaccines against viruses.