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Review
. 2021 Feb 4;7(2):113.
doi: 10.3390/jof7020113.

Techniques for the Assessment of In Vitro and In Vivo Antifungal Combinations

Anne-Laure Bidaud  1 , Patrick Schwarz  2   3 , Guillaume Herbreteau  4 , Eric Dannaoui  1   5
Affiliations
Review

Techniques for the Assessment of In Vitro and In Vivo Antifungal Combinations

Anne-Laure Bidaud et al. J Fungi (Basel). .

Abstract

Systemic fungal infections are associated with high mortality rates despite adequate treatment. Moreover, acquired resistance to antifungals is increasing, which further complicates the therapeutic management. One strategy to overcome antifungal resistance is to use antifungal combinations. In vitro, several techniques are used to assess drug interactions, such as the broth microdilution checkerboard, agar-diffusion methods, and time-kill curves. Currently, the most widely used technique is the checkerboard method. The aim of all these techniques is to determine if the interaction between antifungal agents is synergistic, indifferent, or antagonistic. However, the interpretation of the results remains difficult. Several methods of analysis can be used, based on different theories. The most commonly used method is the calculation of the fractional inhibitory concentration index. Determination of the usefulness of combination treatments in patients needs well-conducted clinical trials, which are difficult. It is therefore important to study antifungal combinations in vivo, in experimental animal models of fungal infections. Although mammalian models have mostly been used, new alternative animal models in invertebrates look promising. To evaluate the antifungal efficacy, the most commonly used criteria are the mortality rate and the fungal load in the _target organs.

Keywords: agar diffusion assay; antifungal combination; antifungal resistance; checkerboard; gradient concentration strip; time-kill curves.

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Conflict of interest statement

During the past five years, Eric Dannaoui has received research grants from MSD and Gilead; travel grants from Gilead, MSD, Pfizer, and Astellas, and speaking fees from Gilead, MSD, and Astellas. Patrick Schwarz has received research grants from Basilea Pharmaceutica, Gilead, and Pfizer, travel grants from Gilead and Pfizer, and a speaking fee from Pfizer. The other authors have no conflicts of interests.

Figures

Figure 1
Figure 1
Summary of steps needed to perform and interpret antifungal combination tests. MIC, minimal inhibitory concentration; MFC, minimal fungicidal concentration; CFU, colony forming unit; FIC, fractional inhibitory concentration; RSA, response-surface analysis; SYN, synergy; ANT, antagonism.
Figure 2
Figure 2
Example of preparation and inoculation of microplates using the checkerboard method based on the EUCAST methodology for antifungal susceptibility testing.
Figure 3
Figure 3
Gradient concentration strip method (Etest) for the determination of antifungal interactions: the fixed ratio protocol.
Figure 4
Figure 4
Example of a synergistic (A), indifferent (B), and antagonistic (C) interaction of two antifungals according to the checkerboard method and calculated by the FIC index. If there is no FIC index > 4, then the lowest FIC index is retained. If there is at least one FIC index > 4, then the highest FIC index is retained. Synergy is defined as a FIC index ≤ 0.5, indifference as a FIC index > 0.5 to 4, and antagonism as a FIC index > 4.
Figure 5
Figure 5
Example of a response-surface analysis for an in vitro antifungal combination experiment. Graphics were generated by the Combenefit software [96].
See this image and copyright information in PMC

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References

    1. Arendrup M.C., Boekhout T., Akova M., Meis J.F., Cornely O.A., Lortholary O. European Society of Clinical Microbiology and Infectious Diseases Fungal Infection Study Group; European Confederation of Medical Mycology ESCMID and ECMM Joint Clinical Guidelines for the Diagnosis and Management of Rare Invasive Yeast Infections. Clin. Microbiol. Infect. 2014;20(Suppl. S3):76–98. doi: 10.1111/1469-0691.12360. - DOI - PubMed
    1. Cuenca-Estrella M., Verweij P.E., Arendrup M.C., Arikan-Akdagli S., Bille J., Donnelly J.P., Jensen H.E., Lass-Flörl C., Richardson M.D., Akova M., et al. ESCMID* Guideline for the Diagnosis and Management of Candida Diseases 2012: Diagnostic Procedures. Clin. Microbiol. Infect. 2012;18(Suppl. S7):9–18. doi: 10.1111/1469-0691.12038. - DOI - PubMed
    1. Arendrup M.C., Patterson T.F. Multidrug-Resistant Candida: Epidemiology, Molecular Mechanisms, and Treatment. J. Infect. Dis. 2017;216:S445–S451. doi: 10.1093/infdis/jix131. - DOI - PubMed
    1. Lestrade P.P.A., Meis J.F., Melchers W.J.G., Verweij P.E. Triazole Resistance in Aspergillus fumigatus: Recent Insights and Challenges for Patient Management. Clin. Microbiol. Infect. 2019;25:799–806. doi: 10.1016/j.cmi.2018.11.027. - DOI - PubMed
    1. Ball B., Bermas A., Carruthers-Lay D., Geddes-McAlister J. Mass Spectrometry-Based Proteomics of Fungal Pathogenesis, Host–Fungal Interactions, and Antifungal Development. J. Fungi. 2019;5:52. doi: 10.3390/jof5020052. - DOI - PMC - PubMed

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