In vitro andin vivo evaluations of LB10517, a novel parenteral broad-spectrum cephalosporin

Thein vitro activity of LB10517, a new catechol-substituted cephalosporin, was compared with those of E-1077, cefpirome and ceftazidime against 1034 clinical isolates collected in Japan. LB10517 showed a broad-spectrum antibacterial activity against a wide range of gram-positive and gram-negative bacteria including non-glucose fermenting rods,Pseudomonas aeruginosa. Against the methicillin-susceptible strains ofStaphylococcus aureus (MSSA) andStreptococcus pyogenes, the MIC₉₀ values of LB10517 which required to inhibit 90% of the strains were 3.13 μg/ml and 0.1 μ/ml, respectively. It was as active as E-1077 but more active than cefpirome and ceftazidime. Methicillin-resistant strains ofS. aureus (MRSA) andEnterococcus spp. were highly resistant to all the test compounds. LB10517 was highly active against most members of the familyEnterobacteriaceae, 90% of which were inhibited at a concentration of less than 0.78 μg/ml, except forEnterobacter cloacae (1.56 μg/ml) andSerratia marcescens (3.13 μg/ml). Its activity was comparable to those of E-1077 and cefpirome but it was greater than that of ceftazidime. AgainstPseudomonas aeruginosa, LB10517 showed the most potent antibacterial activity among the compounds tested. Ninety percent ofP. aeruginosa isolates were susceptible at the concentration of 0.39 μg/ml. Its activity was 32- to 128-fold higher than those of E-1077, cefpirome and ceftazidime. Against imipenem- or ofloxacinresistantP. aeruginosa, LB10517 with MIC₉₀s of 6.25 μg/ml and 3.13 μg/ml, respectively, showed 16-fold more potent activity than the other test compounds. LB10517 showed a relatively high plasma level and long plasma elimination half-life in rats (t_1/2(β), 52 min) and dogs (t_1/2(β), 103 min).