Page "Beta-lactamase" Paragraph 6

Penicillinase was the first β-lactamase to be identified: It was first isolated by Abraham and Chain in 1940 from Gram-negative E. coli even before penicillin entered clinical use, but penicillinase production quickly spread to bacteria that previously did not produce it or produced it only rarely.

Penicillinase-resistant beta-lactams such as methicillin were developed, but there is now widespread resistance to even these.