The first of the antibiotics discovered and produced was penicillin. There are now many other antibiotics in use. These are used to target specific types of bacteria and can be much more effective than penicillin. One of the downsides of using antibiotics is that resistant strains of bacteria can arise. In order to combat these resistant bacteria, scientists are constantly seeking and developing new antibiotics. Overuse of antibiotics and patients not taking the full course prescribed have both contributed to this ever increasing issue.