Antibacterial Activity of Cefsulodin (Sce-129), a new Cephalosporin Derivative, Against Pseudomonas Aeruginosa

Antibacterial activity of Cefsulodin (SCE-129, CFS), a new cephalosporin-derivative, was tested in vitro. The minimum inhibitory concentrations of the new agent against clinically isolated strains of Staphylococcus, Pseudomonas, Klebsiella, Escherichia coli and Enterobacter, were measured and compared to those of CTM (another new cephalosporin-derivative), Sulbenicillin (SBPC) and aminoglycosides. At the concentration less than 25 μg per ml of CFS, the growth of 32 out of 39 strains of Pseudomonas tested was inhibited while only 2 strains out of them were inhibited at the same concentration of SBPC. The concentration over 200 fig per ml of CTM was needed to inhibit the growth of the same strains of Pseudomonas aeruginosa. Except for Kanamycin, the minimum inhibitory concentrations of aminoglycosides (Dibekacin, Tobramycin, Gentamicin and Amikacin) against Pseudomonas were slightly lower than those of CFS. Among the strains of Pseudomonas tested no cross resistance was observed between CFS and aminoglycosides. Substantially, CFS did not show any antibacterial activity against clinical isolates of Klebsiella and Enterobacter. The minimum inhibitory concentrations against the patient strains of Staphylococcus aureus and Escherichia coli were over 6.25 and 25 μg per ml respectively. In conclusion, CFS is the first cephalosporin derivative having a potential antibacterial activity against Pseudomonas and its activity seemed exclusively restricted against this species among gram-negative bacilli. Clinical utilization of such a narrow spectrum but potential antibiotic may provide a therapeutic benefit for treatment of Pseudomonas infections.