Antimicrobial Susceptibility Testing for Colistin: Extended Application of Novel Quantitative and Morphologic Assay Using Scanning Electron Microscopy

Figure 4

Colistin SEM-AST assay applied to Colistin-sensitive and Colistin-resistant strains of E. coli. (a) Evolution of the percentage of viable bacteria for Colistin-resistant strains exposed to Colistin for 120 minutes. (b) SEM images of Colistin-resistant strains exposed to Colistin for 120 minutes. (c) Evolution of the percentage of viable bacteria for Colistin-sensitive strains exposed to Colistin for 120 minutes. (ns: not significant / ^∗∗∗∗: p ≤ 0.0001) (d) SEM images of Colistin-sensitive strains exposed to Colistin for 120 minutes demonstrating morphologic changes (inflation (blue arrow) and lysis (orange arrow)).

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