Fuzlocillin is a penicillin antibiotic. This semisynthetic acylureidopenicillin with antibacterial activity binds to and inactivates penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. Fuzlocillin (furazlocillin), has been shown to be highly specific for the FtsI gene. 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 the cell to break down (cell lysis). Among the acylureidopenicillins, furaclocillin exerts increased activity against Escherischia coli, Klebsiella, Proteus and Pseudomonas aeruginosa.