Interactions of ceftibuten with extended-spectrum beta-lactamases: a bacteriological and enzymatic analysis.

The authors analysed the antibacterial activity of ceftibuten, cefotaxime, ceftazidime and aztreonam against Klebsiella pneumoniae strains, including those which produced novel extended-spectrum beta-lactamases. These molecules were also tested for their susceptibility to cell-free extracts of the corresponding beta-lactamases. Both approaches showed that ceftibuten was not hydrolysed by the CTX-1/TEM-3, SHV-2 and SHV-3 beta-lactamases, while cefotaxime, ceftazidime and aztreonam were hydrolysed. Nevertheless all compounds were substrates for the SHV-4 and SHV-5 beta-lactamases, and the organisms which produced these beta-lactamases showed increased MICs.