A drug that is used to treat infection. It belongs to the family of drugs called antibiotics.

Group of natural or semisynthetic antibacterial antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group; they exert a bacteriocidal as well as bacteriostatic effect on susceptible bacteria by interfering with the final stages of the synthesis of cell wall peptidoglycan.

A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)

(penicillin antibiotic) Any beta-lactam antibiotic derived from Penicillium fungi with bactericidal activity. Penicillin antibiotics bind to and inactivate penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. Inactivation of PBPs interferes with the cross-linkage of peptidoglycan chains necessary for bacterial cell wall strength and rigidity. This interrupts bacterial cell wall synthesis and results in the weakening of the bacterial cell wall, eventually causing cell lysis.

Penicillins are beta-lactam antibiotics that are bactericidal by unknown mechanisms but perhaps by activating autolytic enzymes that destroy the cell wall in some bacteria.

Penicillin, one of the first and still one of the most widely used antibiotic agents, derived from the Penicillium mold. In 1928 Scottish bacteriologist Alexander Fleming first observed that colonies of the bacterium Staphylococcus aureus failed to grow in those areas of a culture that had been...