The 50th anniversary of the discovery of 6-aminopenicillanic acid (6-APA).

This year (2007) marks the 50th anniversary of [corrected] discovery of 6-aminopenicillanic acid (6-APA), the precursor of all semi-synthetic penicillins [corrected] This review, by a scientist who played a major part in the discovery and a physician who participated in the early clinical trials of these antibiotics, tells the story of the discovery and of the early development of the beta-lactam antibiotics that revolutionised the treatment of infections.