Synergistic effects of Miconazole and Polymyxin B on microbial pathogens |
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Authors: | Silvia Pietschmann Katrin Hoffmann Michael Voget Ulrich Pison |
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Institution: | 1.Charité - Universit?tsmedizin Berlin,Klinik für An?sthesiologie und operative Intensivmedizin,Augustenburger Platz 1,Berlin,Germany;2.BAM, Bundesanstalt für Materialforschung und – prüfung,Berlin-Adlershof,Germany;3.ECON AG,Lübeck,Germany |
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Abstract: | The therapeutic value of antibiotics depends on the susceptibility of the infecting microorganism and the pharmacological
profile of the drugs. To assess the value of an antibiotic combination of polymyxin B and miconazole this study examined the
in vitro synergistic potential of the two drugs on Gram-negative and Gram-positive bacteria and yeast. Antifungal and antibacterial
activity was tested by minimum inhibitory concentration (MIC) of broth macrodilution and urea broth microdilution, by fluorescence
microscopy and flow cytometry. Synergism was calculated using the fractional inhibitory concentration index (FICi). With Staphylococcus intermedius as target we found up to an eightfold reduction of the individual MICs when both drugs were combined. However, the FICi was
0.63 suggesting no real interaction between the two drugs. With Escherichia coli, Pseudomonas aeruginosa, and Malassezia pachydermatis as targets the antimicrobial drug combination reduced the MICs of polymyxin B and miconazole from fourfold to hundredfold
resulting in FICi between 0.06 and 0.5 which defines a synergistic action. Thus, if polymyxin B and miconazole are combined
their effect is greater than the sum of the effects observed with polymyxin B and miconazole independently, revealing bactericidal
and fungicidal synergism. Our results indicate a strong therapeutic value for the combination of these antimicrobial agents
against Gram-negative bacteria and yeast and a weaker value against Gram positive bacteria for clinical situations where these
pathogens are involved. |
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Keywords: | Miconazole Polymyxin Antibiotic synergism Otitis externa |
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