Tigemonam activity against clinical isolates of Enterobacteriaceae and Enterobacteriaceae with known mechanisms of resistance to β-lactam antibiotics

Abstract

Tigemonam, a new oral monobactam, was at least as active as aztreonam or carumonam against clinical isolates of Enterobacteriaceae (MIC₉₀ : 0·06–16 mg/l). Tigemonam was very stable in the presence of classical plasmid mediated β-lactamases but its MICs were increased (4–256 mg/l) in the presence of new broad-spectrum plasmid mediated β-lactamases (either TEM of SHV derivatives). Increased MICs (0·25–8 mg/l) were also observed for different isogenic mutants of Enterobacteriaceae, which either produced high levels of chromosome-encoded cephalosporinases, or had a permeability defect.