Bacteriological Comparison of the Activities of Ceftriaxone, a New Long-acting Cephalosporin, with Those of Other New Cephalosporins

抄録

In vitro antibacterial activities of a new cephalosporin, ceftriaxone, were bacteriologically characterized in comparison with those of cefotaxime and ceftizoxime. Minimal inhibitory concentrations (MIC) of cefriaxone determined on 680 fresh clinical isolates in Japan showed extraordinarily high activity against all gram-negative bacteria. Especially notable was its high activity against Proteeae species and Haemophilus influenzae ; in this respect it was greatly superior to both cefotaxime and ceftizoxime. It also showed high activity against Pseudomonas aeruginosa and some anaerobic pathogens. Against other strains, in general ceftriaxone exhibited activity comparable to those of 2 structurally related cephalosporins, except for Klebsiella sp. and Pseudomonas maltophilia, against which it showed lower activity. Its activity is bactericidal and, in contrast to cefotaxime and ceftizoxime, its minimal bactericidal concentration (MBC) value was less than 3 times the MIC except for Ps. aeruginosa. Its mode of action was morphologically assessed. Ceftriaxone showed an unusually high stability to most bacterial β-lactamases except to so-called cefuroximases from Bacteroides fragilis, Pseudomonas cepacia and Proteus vulgaris. In addition, ceftriaxone was found to be a very potent inhibitor of cephaloridine hydrolysis by various β-lactamases.