Combinations of three antimicrobial agents(IV). The in vitro combined effect of three antimicrobial agents analyzed by the three-dimensional checkerboard method using a personal-computer system

Akira Watanabe, Naoto Kitamura, Kotaro Oizumi, Yoshihiro Honda, Reiko Ono, Yutaka Tokue, Satoru Shoji, Masakichi Motomiya

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We have devised a new method for the analysis of the in vitro combined effect of three antimicrobial agents by using the three-dimensional checkerboard method as reported by us previously, in which a new program designed by us for a personal computer system (NEC P-9801, Nihon-Denki Co. Ltd., Japan) was applied. 1.5×10-4ml of an overnight culture of 87 strains consisting of 10 strains of Staphylococcus aureus, 17 of Escherichia coli and 20 each of Klebsiella pneumoniae, Serratia marcescens and Pseudomonas aeruginosa were inoculated into the microtiter plates containing varying concentrations of piperacillin (PIPC), amikacin (AMK) and minocycline (MINO) which were prepared by the MIC 2000 system based on the three-dimensional checkerboard method. The MIC values were input into the program after 20 hours' incubation at 37°C, and then VUS (volume under the surface) values, VUS index and optimum combinations of three agents were calculated for each strain and species. A VUS index of less than 0.75 was evaluated as “synergism”, one between 0.75 and 1.0 as “partial synergism”. The effect of combination as “indifference” when the VUS index was 1. 0 and as “antagonism” when it was more than 1.0. The combination of the three agents was found to be synergistic against all the species as shown by a mean VUS index of 0.702. The mean VUS index for each species was 0.867 against S. aureus, less than 0.679 against E. coli, 0.578 against K. pneumoniae, 0.726 against S. marcescens and 0.847 against P. aeruginosa. We conclude from the above results that the computer-aided three-dimensional checkerboard method is useful for the analysis of the in vitro combined effect of three antimicrobial agents.

    Original languageEnglish
    Pages (from-to)324-329
    Number of pages6
    JournalChemotherapy
    Volume38
    Issue number4
    DOIs
    Publication statusPublished - 1990 Jan 1

    Keywords

    • VUS
    • VUS index

    ASJC Scopus subject areas

    • Pharmacology (medical)
    • Infectious Diseases
    • Pharmacology
    • Drug Discovery
    • Oncology

    Fingerprint Dive into the research topics of 'Combinations of three antimicrobial agents(IV). The in vitro combined effect of three antimicrobial agents analyzed by the three-dimensional checkerboard method using a personal-computer system'. Together they form a unique fingerprint.

    Cite this