Bacteriological studies with cefsulodin (CGP 7174/E), the first antipseudomonal cephalosporin

The new cephalosporin, cefsulodin, has considerable antibacterial activity against Pseudomonas aeruginosa. When 217 strains of Ps. aeruginosa were tested against both azlocillin and cefsulodin, 26.3% were found to have the same minimal inhibitory concentration (MIC); the MIC for azlocillin was lower than that for cefsulodin in 16.6% of strains, but higher in 57.1%. 22 gentamicin-resistant strains were all susceptible to cefsulodin. Biophotometer investigations demonstrate less bactericidal effects for cefsulodin and azlocillin than for carbenicillin and ticarcillin using higher inocula than used in the agar of tube dilution test. Cefsulodin and gentamicin are synergistic against Ps. aeruginosa. Using high pressure liquid chromatography and biological techniques, cefsulodin is found to be moderately stable in solution and in standard solid laboratory media.