The inhibition of bacterial beta-lactamases by some monocyclic beta-lactams

The inhibition characteristics of 25 monocyclic beta-lactams mainly with an amido function at C3 have been studied against the beta-lactamases produced by 4 bacterial types. Significant levels of inhibition were found for only a few of the compounds tested and primarily against Staphylococcus beta-lactamase. The most active inhibitor tested, 3-p-nitrophenylacetamido-4-phenylazetidin-2-one, was found to require a cis geometry, the trans isomer being almost inactive.