Antibiotics have played a major role in our society thanks to Sir Alexander Fleming"s careful observations in 1928. Without it, many lives would be in danger due to infectious diseases. Antibiotics are chemical substances produced by various species of microorganisms and other living systems that are capable in small concentrations of inhibiting the growth of or killing bacteria and other microorganisms. These organisms can be bacteria, viruses, fungi, or animals called protozoa. A particular group of these agents is made up of drugs called antibiotics, from the Greek word anti "against" and bios "life". Some antibiotics are produced from living...
bacteria have been discovered.

Another use of antibiotics is as additives to the feed of animals. Chickens and beef cattle, for example, can be fed with these additives for better weight gains and to speed their growth.

Current work in antibiotics is largely in the area of viruses. Although some antivirals are available, most have toxic effects so severe that they can be used only in life-threatening diseases where the negative effects are the lesser danger. Preliminary studies, however, are reporting success in the development of safer antiviral drugs, and their use should be possible within the near future.