Unraveling Direct Correlations between Membrane Nanodomain Reorganization and Antimicrobial Resistance Evolution in bacterial Cells

Bacterial drug resistance is a major global health emergency which needs newer approaches for its detection especially those which are rapid and sensitive at single cell level. One of the major limitation of existing antimicrobial resistance (AMR) screening is that it relies on culturing bacterial samples, which is time and resource intensive or on detection of known mutations which impart resistance. Here we provide the first evidence for existence of direct correlations between nanoscale dynamical reorganization in bacterial cell membranes in cells undergoing evolution of phenotypic resistance under sub-lethal dosage of antibiotic Colistin. While super-resolution fluorescence microscopy in combination with fluorescence correlation spectroscopy enables probing dynamical lipid nanodomains on single E. coli cells undergoing AMR evolution, high-resolution atomic force microscopy provides information on nanoscale morphological changes in the same cell population. Interestingly our study also reveals intricate correlations between nanoscale bacterial membrane organization and biochemical signalling responses that eventually drive evolution of antimicrobial resistance. In addition we detect signatures of cooperative lipid motion and dynamic heterogeneity as quantified through the non-Gaussian parameter for lipid number fluctuations in the illumination volume.Our study suggests subtle feedback mechanism for emergence of antimicrobial resistance through biochemical signaling that leads to membrane compositional changes. These compositional changes alters these membrane nanoscale parameters to mitigate the antibiotic mediated stress and increases survival probability of the cell population which thus becomes more resistant. Our study could thus lead to development of a fundamentally new approach with high resolution and sensitivity, to infer about antimicrobial resistance evolution, which could also be applicable to other Gram-negative strains and membrane-targeting antibiotics