Chemical Structure / Formula of Monobactams (Aztreonam)
Formula: C13H17N5O8S2 Monobactams (Aztreonam)
Unique feature: Single β-lactam ring (monocyclic), unlike penicillins and cephalosporins.

Mechanism of Action
Binds to PBP-3, inhibiting bacterial cell wall synthesis.
Selective for aerobic Gram-negative bacteria, including Pseudomonas aeruginosa.
Uses
Treats serious Gram-negative infections, including pneumonia, sepsis, and UTIs.
Safe for penicillin-allergic patients (no cross-reactivity).
Side Effects
Common: Rash, nausea.
Serious: Liver enzyme elevation, eosinophilia.