[Synergistic action of cefodizime with other antimicrobial agents on clinically isolated microorganisms. II. Synergistic action with sisomicin].
Cefodizime (CDZM) possesses a broad antimicrobial spectrum and a relatively long half life in the blood. In addition, it shows excellent therapeutic efficacies in the treatment of infections in leukopenic animal models, hence it is expected that CDZM may have good efficacies against various infections in immunocompromised hosts. In the meantime, sisomicin (SISO) not only has strong antibacterial activities against Gram-negative rods (GNR), but has relatively low nephrotoxicity and ototoxicity. Thus, we examined antibacterial effectiveness of the combination of CDZM and SISO against clinical isolates in vitro. 1. Antibacterial effects of CDZM+SISO combination were examined using SISO susceptible strains of Escherichia coli, Citrobacter freundii, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, Proteus vulgaris, Morganella morganii and Pseudomonas aeruginosa. Observations that the combination of the 2 drugs showed FIC indices between less than 0.5-less than 1.0 against most of these strains at SISO concentrations of 1 MIC or sub MIC levels strongly suggested the presence of a synergistic action between the 2 drugs against SISO susceptible strains of GNR. 2. Of the strains tested, 10% of C. freundii, 6.7% of E. cloacae, 63.3% of S. marcescens, 23.3% of P. vulgaris and 18.0% of P. aeruginosa were found to be resistant to SISO, and little synergistic effect of the 2 drugs was observed against these strains. 3. As the synergistic effect of the 2 drugs against GNR was observed against SISO susceptible strains including those which were resistant to CDZM, but not against those strains which were resistant to SISO, it seems reasonable to conclude that the appearance of the synergistic effect between the 2 drugs depends on the activity of SISO.
Deguchi
K
K
Section of Studies, Tokyo Clinical Research Center.
Yokota
N
N
Koguchi
M
M
Nakane
Y
Y
Suzuki
Y
Y
Fukayama
S
S
Ishihara
R
R
D002439:Cefotaxime / Q000031:analogs & derivatives* / Q000494:pharmacology; D004359:Drug Therapy, Combination / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D012853:Sisomicin / Q000494:pharmacology*
D002439:Cefotaxime; D012853:Sisomicin; C033356:cefodizime