Some of the diseases/illnesses that penicillin treats includes: pneumonia, meningitis, erysipelas, scarlet fever, diphtheria, blood poisoning, syphilis, gangrene, strep throat and gonorrhea.Penicillin works to treat illnesses/diseases by killing bacteria and arresting its growth. It only kills the bacteria that is growing and reproducing, not those which are stationery.

A penicillin colony will begin looking like a fluffy white mass, almost resembling a cotton ball. A few days later, the colony will turn dark green. As it is turning green, it is also secreting bright yellow drops of liquid. This liquid is what we call penicillin.