Nanoscale analysis of the effects of antibiotics and CX1 on a Pseudomonas aeruginosa multidrug-resistant strain

Abstract

Drug resistance is a challenge that can be addressed using nanotechnology. We focused on the resistance of the bacteria Pseudomonas aeruginosa and investigated, using Atomic Force Microscopy (AFM), the behavior of a reference strain and of a multidrug resistant clinical strain, submitted to two antibiotics and to an innovative antibacterial drug (CX1). We measured the morphology, surface roughness and elasticity of the bacteria under physiological conditions and exposed to the antibacterial molecules. To go further in the molecules action mechanism, we explored the bacterial cell wall nanoscale organization using functionalized AFM tips. We have demonstrated that affected cells have a molecularly disorganized cell wall; surprisingly long molecules being pulled off from the cell wall by a lectin probe. Finally, we have elucidated the mechanism of action of CX1: it destroys the outer membrane of the bacteria as demonstrated by the results on artificial phospholipidic membranes and on the resistant strain.

Impact of Tetracationic Calix[4]arene Conformation—from Conic Structure to Expanded Bolaform—on Their Antibacterial and Antimycobacterial Activities

“…The effect of active polycationic calix[4]arene systems was analyzed as originating from the disruption of the bacterial membrane, associated with the modification of electrophoretic mobility and increasing of the membrane permeability . Atomic force microscopy (AFM) investigations have enabled us to verify denaturation of the bacterial wall with loss of elasticity and hole formation in the outer membrane . Combined with physicochemical investigations on various eukaryotic and prokaryotic membrane models with Langmuir balance, these first results have indeed validated our initial hypothesis, based on strong synergized electrostatic interactions between the constrained positive charges of the guanidinium groups and membrane anions representative of the global negative charge of bacterial surfaces.…”

Mapping HA‐tagged protein at the surface of living cells by atomic force microscopy

“…This can be achieved through the use of heterobifunctionalized polyethylene glycol (PEG; Kamruzzahan et al , ; Ebner et al , ; Wildling et al , ) or, as we decided in our study, through the use of an aldehyde–phosphorus dendrimer, as we previously described (Jauvert et al , ). This strategy developed in our team in 2012, and already used for probing the surface of live bacteria (Formosa et al , ), consists in making “dendritips” by reacting amino‐functionalized AFM tips with dendrimers, therefore leading to dendrimer‐activated tips. Then, the free aldehyde functions at the surface of the dendrimers are available to react with amino‐functions present on every protein and on many biomolecules.…”

Morphological and ultrastructural changes in bacterial cells as an indicator of antibacterial mechanism of action

“…[36], and tobramycin [204]), and peptidoglycan synthesis (several β-lactams [55,83,141,174]). Lastly, 'ghost cells', a term used to describe lysed bacteria devoid or near-devoid of cytoplasm (Fig.…”