Antimicrobial Effectiveness of Kanamycin, Aminosidin, B8-K8, Sisomicin, Gentamicin and Tobramycin Combined with Carbenicillin or Cephalothin Against Gram-Negative Rods

SUMMARY The activity of kanamycin, aminosidin, BB-K8, sisomicin, gentamicin and tobramycin, has been compared in vitro against a variety of Gram-negative micro-organisms isolated from hospital patients. Clear differences in activity against Pseudomonas aeruginosa were observed between these antibiotics, tobramycin, BB-K8 and sisomicin being more active than the others. No major broadening of the spectrum occurred when carbenicillin and cephalothin were combined with the more active aminoglycosides, tobramycin, sisomicin and BB-K8. Synergism was observed against more than 50% of the strains of Ps. aeruginosa when BB-K8, tobramycin, sisomicin or gentamicin were combined with carbenicillin and against more than 50% of klebsiella strains when aminosidin, kanamycin or gentamicin were combined with cephalothin.