Abstract
The minimal inhibitory concentration (MIC) assay uses agar or broth dilution methods to measure, under defined test conditions, the lowest effective concentration of an antimicrobial agent that inhibits visible growth of a bacterium of interest. This assay is used to test the susceptibilities of bacterial isolates and of novel antimicrobial drugs, and is typically done in nutrient-rich laboratory media that have little relevance to in vivo conditions. As an extension to our original protocol on MIC assays (also published in Nature Protocols), here we describe the application of the MIC broth microdilution assay to test antimicrobial susceptibility in conditions that are more physiologically relevant to infections observed in the clinic. Specifically, we describe a platform that can be applied to the preparation of medium that mimics lung and wound exudate or blood conditions for the growth and susceptibility testing of bacteria, including ESKAPE pathogens. This protocol can also be applied to most physiologically relevant liquid medium and aerobic pathogens, and takes 3–4 d to complete.
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Acknowledgements
Our own antibiotics research is funded by the Canadian Institutes for Health Research Foundation grant FDN-154287. C.R.B. received a Doctoral Studentship Award from Cystic Fibrosis Canada. R.E.W.H. holds a Canada Research Chair in Health and Genomics and a UBC Killam Professorship.
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Key reference using this protocol
Belanger C. R. et al. Proc. Natl Acad. Sci. USA 117, 33519–33529 (2020): https://doi.org/10.1073/pnas.2007626117
This protocol is an extension to: Nat. Protoc. 3, 163–175 (2008): https://doi.org/10.1038/nprot.2007.521
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Belanger, C.R., Hancock, R.E.W. Testing physiologically relevant conditions in minimal inhibitory concentration assays. Nat Protoc 16, 3761–3774 (2021). https://doi.org/10.1038/s41596-021-00572-8
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DOI: https://doi.org/10.1038/s41596-021-00572-8
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