mecillinam

Mecillinam is a narrow-spectrum amidinopenicillin antibiotic with a unique mechanism of action that distinguishes it from other beta-lactams. While most penicillins and cephalosporins primarily target Penicillin-Binding Proteins 1 and 3 (PBP1 and PBP3) to inhibit cell wall synthesis, mecillinam binds with high affinity and specificity to Penicillin-Binding Protein 2 (PBP2). This binding interferes with the maintenance of the rod-like shape of Gram-negative bacteria, causing them to transform into large, fragile spherical cells (spheroplasts) that eventually undergo osmotic lysis. It is particularly potent against Enterobacteriaceae, including *Escherichia coli*, *Klebsiella*, and *Salmonella* species, but lacks significant activity against Gram-positive bacteria and *Pseudomonas aeruginosa*. Developed by Leo Pharma, mecillinam is used parenterally for serious infections, while its pivaloyloxymethyl ester prodrug, pivmecillinam, is used orally for uncomplicated urinary tract infections.

Brand names

SelexidCoactiveAmdinocillineMecilline

Other names

amdinocillinamidinopenicillin