Possibilities of transmission electron microscopy in assessing the quality of bacterial cells and microbial population.

Determination of changes in the morphostructure of microorganisms under the influence of antibiotics, disinfectants, biocins, physical and chemical agents is carried out using the method of visualization of ultrathin sections in a transmission electron microscope. The aim is to develop methodological techniques for express preparation and visualization of the ultrastructure of bacteria in a transmission electron microscope to detect structural damage to cells and assess the quality of the microbial population. A technique of accelerated sample preparation for visualization of the fine structure of bacteria and diagnosis of structural damage to cells in a transmission electron microscope has been developed. The use of this method will make it possible to more effectively investigate the mechanisms of inactivation of microorganisms at different stages of contact with antibiotics, disinfectants, biocines, including various stressful, damaging and lethal physical and chemical effects.

Peculiarities of the ultrastructure of mixed biofilms of the causing agent of diphtheria and conditionally pathogenic microorganisms isolated from the human respiratory tract.

In the post-epidemic period, the circulation of the causative agent of diphtheria in the population is maintained due to the carrier of bacteria. Entering an organism with a high level of antitoxic immunity, the pathogen enters into intermicrobial interactions with representatives of the opportunistic microflora inhabiting the respiratory tract and forms a biofilm. MATERIALS AND METHODS: Modeling of the biofilm formation process was carried out using the strains C.diphtheriae gravis tox+№. 665, C.pseudodiphtheriticum, S.aureus. Biofilm samples were placed on the stage of a scanning electron microscope and gold-sputtered in an EicoIB-3 ioncoater vacuum deposition unit (Eico, Japan) at an ion current of 6-8 mA. The samples obtained were examined in a JEOL 6510LB scanning electronmicroscope. («JEOL¼ company, Japan) at an accelerating voltage of 30 kV. RESULTS: Electron microscopic examination of samples of biofilms C. diphtheriae gravis tox+ № 665 and opportunistic microorganisms shows groups of 2-7 young bacterial cells packed into a single microcapsule. Much more voluminous accumulations of bacterial cells (more than 10-12) are typical for biofilm samples represented by C. diphtheriae gravis tox+№ 665 and S. aureus cells. On the surface of the biofilm, young bacterial cells with an intact structure are located at various stages of active division. The conglomerates of bacterial cells, covered with a common intermicrobial matrix, adhere tightly to each other and form a multilayer biofilm. CONCLUSION: Features of the ultrastructure of biofilms containing strains of C. diphtheriae and opportunistic bacteria, especially antibiotic-resistant bacteria inhabiting the respiratory tract, can contribute to long-term persistence of the pathogen of diphtheria in the body. They not only significantly complicate the access of antibacterial drugs, but also interfere with the isolation of C.diphtheriae during bacteriological research.