The discovery of penicillin was very significant in that it gives doctors an effective way to treat bacterial infections. This is important because before penicillin, even the smallest injury could lead to death. Even a small cut can still give space to enter the body. Before penicillin and antibiotics, doctors resorted to methods like bloodletting and applying chemicals like mercury to the body. These methods were not very effective and led to very dangerous side effects, so doctors were not able to effectively treat their patients. However, penicillin provided the solution, as it is able to prevent bacteria reproduction by breaking bacterial cell walls, so it can effectively fight against bacteria in the human body.