"Penicillium notatum" was discovered first by the doctor Alexander Fleming, in 1929.
The penicillin is a bacteriocidal antibiotic, because it kills bacteria. Penicillin impedes the process of division of cells, inactivating transpeptidase enzyme, which is responsible for the cross-links of peptidoglycan strands that form the cell walls.
Penicillin can kill active growing bacteria but it cannot kill the spores, hence, the duration of medication and association with aminoglycosides can enhance its effectiveness.
The intake of penicillin in case of viral disease can lead to antibiotic resistance. The short duration of treatment of bacterial infections can also be a factor that can lead to antibiotic restistance. The risk of developing antibiotic resistance can be avoided if the advice of the doctor is followed and the use of antibiotics is well understood.
Penicillin kills bacteria by not allowing the bacteria to form new cell walls. The penicillin interferes with the process until the cell walls eventually become weak and burst.