CAYSTON is an inhalation-specific formulation of aztreonam, a monobactam antibiotic

Monobactams Inhibit Pseudomonas aeruginosa (Pa) Cell Wall Synthesis

  • Monobactams are structurally different from other beta-lactam antibiotics (eg, penicillins, cephalosporins, carbapenems) due to a monocyclic nucleus.
  • This nucleus contains several side chains: sulfonic acid in the 1-position activates the nucleus, an aminothiazolyl oxime side chain in the 3-position confers specificity for aerobic Gram-negative bacteria including Pseudomonas spp., and a methyl group in the 4-position enhances beta-lactamase stability.
  • Aztreonam exhibits activity in vitro against Gram-negative aerobic pathogens including Pa.
  • Aztreonam binds to penicillin-binding proteins of susceptible bacteria, leading to inhibition of bacterial cell wall synthesis and death of the cell.
  • Aztreonam activity is not decreased in the presence of CF lung secretions.
Mechanism of Action graphMechanism of Action graph