Azthreonam: in vitro activity against urinary pathogens

The in vitro activity of azthreonam, a novel monocyclic beta-lactam antibiotic, was investigated for Gram negative urinary pathogens by determining the susceptibilities of 105 consecutive isolates from specimens submitted to the Auckland Hospital microbiology laboratory. All were sensitive or of intermediate sensitivity by disc diffusion testing. Minimum inhibitory concentrations (MICs) were 0.25 mg/l for 97 per cent of Enterobacteriaceae and ranged from 2-16 mg/l for Pseudomonas aeruginosa. Of antibiotics tested routinely in this laboratory only tobramycin showed comparable potency.