In Vitro Effectiveness of Kanamycin and Kanamycin/Cephalothin AgainstKlebsiella

Abstract

Twenty-five clinical isolates of Klebsiella were tested for in vitro sensitivity to kanamycin, cephalothin, tetracycline and chloramphenicol. With both inhibitory and bactericidal tests, kanamycin was the most consistently effective, with only 2 strains showing resistance. Kanamycin/cephalothin was superior to tetracy-cline/streptomycin and chloramphenicol/streptomycin when compared in concentrations attainable in the blood stream. Synergism was demonstrated with bactericidal tests for 13 of the 25 strains with kanamycin/ cephalothin; in 3 other strains, the combination was additive; no antagonism was observed. All 25 strains were killed by the combination in concentrations of 8 mcg per ml or less. With one strain, rapid in vitro development of resistance occurred with both kanamycin and cephalothin. This was delayed when the organism was exposed to the 2 agents in combination. Since many Klebsiella infections are associated with high mortality, despite its taxicity, kanamycin should be considered more prominently in the selection of chemotherapeutic agents, either for use alone or in combination with cephalothin.