Aztreonam

A synthetic β-lactam antibiotic of the monobactam class; active against clinical isolates of E. coli, S. marcescens, P. aeruginosa, Klebsiella species, Proteus species, and Enterobacter species (MICs = S. pneumoniae, B. fragilis, and S. faecalis (MICs = >100 µg/ml for all); interferes with peptidoglycan synthesis in the bacterial cell wall of the Gram-negative bacteria E. coli, P. vulgaris, E. cloacae, K. pneumoniae, and P. aeruginosa by inhibiting penicillin-binding protein 3 (PBP3; IC100 = 0.1 µg/ml for all); increases survival in mice with systemic Gram-negative bacterial infections (ED50s = 0.1-24.7 mg/kg)