Interspecies Interaction of Bacteria Listeria monocytogenes, Yersinia pseudotuberculosis, and Marine Saprotrophs during Long-Term Culturing in Biofilms.

All bacterial strains studied retained the viability and ability to form both mono- and polycultural biofilms under conditions of long-term culturing in artificial seawater at 6°C and without addition of nutrients. Bacillus sp. and Pseudomonas japonica presumably stimulated the growth and reproduction of the pathogenic bacteria Listeria monocytogenes and Yersinia pseudotuberculosis. Preserved cell viability in a monoculture biofilm for a long period without adding a food source can indicate allolysis. At the same time, in a polycultural biofilm, the metabolites secreted by saprotrophic strains can stimulate the growth of L. monocytogenes and Y. pseudotuberculosis.

Biosafety of personnel of microbiological laboratories in the context of the Federal Law of the Russian Federation № 492-FZ of December 30, 2020 «On the biological safety of the Russian Federation¼.

One of the most important requirements for the personnel of microbiological laboratories working with pathogenic and infectious agents is the observance of precautionary measures and the implementation of a set of preventive measures, collectively interpreted as biological safety (biosafety). To a large extent, biosafety problems are also relevant for all clinical laboratories working with biosubstrates, with the potential threat of containing pathogens of bloodborne infections in them. On December 30, 2020, the President of the Russian Federation signed Federal Law № 492 «On the Biological Safety of the Russian Federation¼ (№ 492-FZ), which regulates the basic legal norms and regulation of biosafety issues, as well as a list of measures to prevent the risks of the spread of infections due to accidents, bioterrorist acts and sabotage. The current pandemic of the coronavirus infection COVID-19 has demonstrated, on the one hand, the epidemiological vulnerability of the single world space, and on the other hand, the decisive influence of biological emergencies on the emergence of negative political and economic processes in the world community. In this regard, the issues of ensuring biosafety in the work of microbiological laboratories in the context of protecting personnel and the environment from accidental or unintentional spread of infections are relevant. Working with pathogenic biological agents in microbiological laboratories is constantly associated with the risk of accidents and possible laboratory infection (laboratory-acquired infections) of employees, environmental pollution if the requirements of regulatory documents on biological safety are not met. In accordance with the requirements of № 492-FZ, in order to prevent biological threats, it is necessary to create a system for monitoring biological risks in microbiological laboratories when working with any infected material.

Ultrastructural Changes of Bacteria in Static Cultures of Yersinia pseudotuberculosis under Long Storage under Conditions of Low Temperature.

Electron microscopy study revealed changes in the ultrastructure of bacteria of Yersinia pseudotuberculosis strains characterized by significantly reduced reproductive ability and virulence potential after long-term storage at low temperature of 4-8°C. Most bacterial cells contained dark cytosol with reduced cellular material or empty cytosol, while the cell wall was preserved. The revealed ultrastructural changes in the bacterial cells of the static culture of Y. pseudotuberculosis suggest that storage of strains under low positive temperatures could induce the transition of the majority of bacterial cell population to a dormant, non-cultivated state with a decrease in their virulence. This fact is of great scientific and applied importance in studies of causative agents of saprozoonoses, including pseudotuberculosis, which has the etiopathogenetic background of persistent infection.

Simplified formats of modern biosensors: 60 years of using immunochromatographic test systems in laboratory diagnostics.

Immunochromatographic test systems known to foreign laboratory diagnostic experts as lateral flow immunoassay (LFIA) are simplified tape formats of modern biosensors. For 60 years, they have been widely used for the rapid detection of target molecules (ligands) in biosubstrates and the diagnosis of many diseases and conditions. The growing popularity of these test systems for providing medical care or diagnostics in developing countries, medical facilities, in emergency situations, as well as for individual home use by patients while monitoring their health are the main factors contributing to the continuous development and improvement of these methods, the emergence of a new generation of formats. The attractiveness and popularity of these fast, easy-to-use, inexpensive and portable diagnostic tools is associated primarily with their high analytical sensitivity and specificity, as well as the ease of interpretation of the results. These qualities have passed the test of time, and today LFIA test systems are fully consistent with the modern world concept of «point-of-care testing¼, finding wide application not only in medicine, but also in ecology, veterinary medicine, and agriculture. This review will highlight the modern principles of designing the most widely used formats of immunochromatographic test systems for clinical laboratory diagnostics, summarize the main advantages and disadvantages of the method, as well as current achievements and prospects of LFIA technology. Modern innovations aimed at improving the analytical characteristics of LFIA technology are interesting, promising and can bring additional benefits to immunochromatographic platforms that have gained popularity and attractiveness for six decades.

[A comparative evaluation of differential and diagnostic properties of the Serov's agar medium and the base of selective agar for isolating enteropathogenic yersinia.]

The interest in the problem of enterоpathogenic yersinioses in the world is associated with the ubiquitous distribution of these infections and the clinical significance of their pathogenic agents, Yersinia enterocolitica and Y. pseudotuberculosis. In spite of the novel diagnostic tools, microbiological cultivation on nutrient media still remains the main method of their verification. As an agar of choice, American and European practical guidelines recommend a selective agar for Yersinia, which is widely used in many countries for isolating pathogenic Yersinia from clinical material. The authors compare the differential and diagnostic properties of the base of selective agar with those of the Serov's agar medium, as one of the substrates for Yersinia recommended by the current Russian regulatory documents. Based on the studies conducted, a conclusion has been made that the Serov's agar medium is not inferior to its foreign analogue in the differential and diagnostic properties for identification of enteropathogenic Yersinia.