INTERACTIONS OF CEFTIBUTEN WITH EXTENDED-SPECTRUM BETA-LACTAMASES - ABACTERIOLOGICAL AND ENZYMATIC ANALYSIS

The authors analysed the antibacterial activity of ceftibuten, cefotax ime, 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-fr ee extracts of the corresponding beta-lactamases. Both approaches show ed that ceftibuten was not hydrolysed by the CTX-1/TEM-3, SHV-2 and SH V-3 beta-lactamases, while cefotaxime, ceftazidime and aztreonam were hydrolysed. Nevertheless all compounds were substrates for the SHV-4 a nd SHV-5 beta-lactamases, and the organisms which produced these beta- lactamases showed increased MICs.