Effect of conalbumin on the activity of Syn 2190, a 1,5 dihydroxy-4-pyridon monobactam inhibitor of AmpC beta-lactamases

Syn 2190, a 1,5 dihydroxy-4-pyridon monobactam inhibitor of AmpC enzymes, w as tested against beta-lactamase-producing bacteria with piperacillin, pipe racillin-tazobactam and ceftazidime as partner drugs. In the presence of co nalbumin as an iron chelator, Syn 2190 potentiated these drugs against most AmpC producers, although Klebsiella spp. with plasmidic AmpC enzymes were an exception. Potentiation was much weaker without conalbumin, suggesting t hat Syn 2190 exploits a ferric uptake pathway, as do catecholic cephalospor ins. Syn 2190 had little ability to potentiate partner drugs against strain s with other beta-lactamase types but, with conalbumin, increased the activ ity of piperacillin-tazobactam against Escherichia coil transconjugants pro ducing various class A or D enzymes.