In-vitro and in-vivo antibacterial activities of E1040, a new cephalosporin with potent antipseudomonal activity.

E1040 is a new parenteral cephalosporin with a broad antibacterial spectrum and potent activity against Gram-negative bacteria including Pseudomonas aeruginosa. The in-vitro activities of E1040 against clinical isolates of Enterobacter cloacae, Ent. aerogenes, Providencia rettgeri, and Morganella morganii were superior to those of ceftazidime, cefoperazone, cefmenoxime, and cefuzonam. The activities of E1040 against Gram-positive cocci were comparable with those of ceftazidime, but it was less active than cefmenoxime, cefuzonam, and cefoperazone. Against Ps. aeruginosa, E1040 was more potent than the other compounds, with an MIC90 of 0.39 mg/l, 1/16 that of ceftazidime. The in-vitro activity of E1040 was well sustained in vivo as shown by results obtained in experimental infections in mice. In particular, E1040 was the most active drug against Ps. aeruginosa including gentamicin-resistant and beta-lactamase-overproducing strains. Morphological studies using a scanning electron microscope and a phase-contrast microscope showed that E1040 caused spheroplast and bulge formation in Ps. aeruginosa at low concentrations.