Rapid Detection of Suspension and Biofilm Nanomotion and Antibiotic Resistance Estimation.

Objectives: To develop a system for the rapid detection of 173-p1 antibiotic resistance (to ensure reliable fixation of bacteria on a cantilever without losing their nanomotion, to show that nanomotion is due to bacterial metabolism, to compare the nanomotion of bacteria in suspension form and inside of the biofilms), to study the sensitivity/resistance of 173-p1 to antibiotics (lincomycin, ceftriaxone and doxycycline) using the oscillation method of atomic force microscopy and to evaluate the sensitivity and speed of the method in comparison with the classical disk diffusion method.

Methods: The oscillation mode of atomic force microscopy, scanning electron microscopy and the classical disk diffusion method were used for a complex parallel study of 173-p1 antibiotic resistance, which included testing of fixing agents (poly-L-lysine, rosin and fibronectin), comparison of bacterial metabolism in a set of media (normal saline solution, meat-peptone broth and lysogeny broth) and assessment of antibiotic sensitivity/resistance per se.

Results: A method for express testing of antibiotic resistance using AFM was developed; it is shown that bacterial nanomotion directly correlates with bacteria metabolic activity and that bacterial nanomotion is more easily detected in suspension form, rather than in biofilms.

Differences in bacteria nanomotion profiles and neutrophil nanomotion during phagocytosis.

The main goal of this work is to highlight the connection between nanomotion and the metabolic activity of living cells. We therefore monitored the nanomotion of four different clinical strains of bacteria (prokaryotes) and the bacterial phagocytosis by neutrophil granulocytes (eukaryotes). All clinical strains of bacteria, regardless of their biochemical profile, showed pronounced fluctuations.

Conditioning adhesive contacts between the neutrophils and the endotheliocytes by Staphylococcus aureus.

We have developed a model for evaluating the integral intercellular interactions in the "endotheliocyte-neutrophil" system and have shown the high variability of adhesion contacts in different donors associated with different expression profiles of neutrophils. Two methods (forсe spectroscopy-spectroscopy and scanning ion-conductance microscopy) showed a decrease in the rigidity of the membrane-cytoskeletal complex of neutrophils under the influence of Staphylococcus aureus 2879 M. Adding this strain to the "endotheliocyte-neutrophil" system caused a statistically significant decrease in the adhesion force and adhesion work, which indicates a change in the expression profile and physicochemical properties of membranes of both types of interacting cells (neutrophils and endotheliocytes).