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. 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 , from the Greek word ....