In 1928,a scottish scientist named alexander fleming was researching a kind of bacteria called staphylococcus. he conducted experiments with the bacteria in dishes. fleming was messy and absent-minded. when he left his laboratory to go on vacations. instead of cleaning up,he left the bacteria in the dish. when he returned,he noticed that mold had grown in the dishes while he was gone. he could have just thrown the dishes away. fortunately,instead,he looked at them under microscope. fleming found that the area around the mold was free of bacteria.he realized that the dangerous bacteria must have been dissolved by the mold. these dirty dishes led to discovery of penicillin,the first antibotics. today,this life-saving drug is used around the world. each year there are 80 million prescriptions written for penicillin in the U.S. alone