Abstract

Mecillinam and pivmecillinam are the first of a new group of penicillins, the amidino penicillins, which differ from other penicillins in having the side chain joined to the β-lactam ring by a β-amidino group rather than a β-acylamino group. The amidino group gives it properties quite different from other β-lactam antibiotics including the cephalosporins and other penicillins, and unlike them it acts on only one enzyme in the biosynthesis of the bacterial cell wall.