In-vitro activity of tigemonam, an oral monobactam, against gram-negative rods, including variants in beta-lactamase-production.

Tigemonam was compared in vitro with other orally active beta-lactams, aztreonam and ciprofloxacin against a selection of Gram-negative clinical isolates and laboratory-derived beta-lactamase-producing variants. Of the orally active beta-lactams, tigemonam was the most potent, with a spectrum of activity similar to that of aztreonam. This included stability to plasmid-mediated beta-lactamases and poor induction of chromosomal beta-lactamases. The susceptibility to Class I enzymes was only clinically significant for derepressed Enterobacter cloacae mutants. Tigemonam may have a valuable role in the management of infection caused by enterobacteria, particularly if bioavailability following oral administration is confirmed in human subjects.