ChEBI: Mecillinam is a penicillin in which the 6beta substituent is [(azepan-1-yl)methylidene]amino; an extended-spectrum penicillin antibiotic that binds specifically to penicillin binding protein 2 (PBP2), and is only considered to be active against Gram-negative bacteria. It has a role as an antibacterial drug and an antiinfective agent.