An antibiotic agent derived
from a mold (a type of fungus) of the genus
Penicillium. It was among the first antibiotics to be discovered,
by Alexander Fleming in 1928.
It was later developed in soluble form and for medical use by Ernst Chain
and Howard Florey in 1940. Since then numerous
penicillin derivatives have been manufactured, extending the range of activity,
overcoming the resistance in some organisms, and allowing some to be taken
by mouth. It is effective in combating a wide range of bacterial infections
by interfering with cell wall production
| 3D model of penicillin.
Created by Michael Ströck and released under the GFDL
| (A) the common penicillin nucleus (6-aminopenicillamic
acid); R is an acyl side chain; (B) G or benzyl penicillin; (C) cloxacillin
Staphylococcus and Streptococcus,
and the bacteria causing the venereal diseases gonorrhea
and syphilis are among the bacteria sensitive
to natural penicillin, while bacilli negative to Gram's
stain, which cause urinary tract infection,septicemia,
etc., are destroyed by semisynthetic penicillins.
Penicillin can produce allergic reactions, including itching and (rarely)
potentially fatal shock. Because some microorganisms
have become resistant to its action, other antibiotics are often used instead.