Journal of microbiology, epidemiology and immunobiology

Introduction. Salmonella Kentucky sequence type ST198 is one of the epidemiologically significant non-typhoidal Salmonella clones worldwide and is characterized by the presence of highly resistant strains and the ability to adapt to different animal hosts and environmental conditions.

The aim of this study was to analyze S. Kentucky strains isolated from various sources in Russia in terms of their phylogenetic position within the global diversity of the pathogen and their genetic characteristics.

Materials and methods. We examined 55 strains of S. Kentucky by whole-genome sequencing, which were isolated from 2010 to 2022 from various sources (clinical strains, food, as well as from farm animals, feed and environmental samples). Whole genome sequencing was performed using Illumina platforms. Phylogenetic analysis based on nucleotide variation analysis included an additional 390 S. Kentucky strains.

Results. Most of the Russian strains (n = 50) belonged to the ST198 sequence type, four strains were ST314 and one strain was ST152. Of the 50 Russian sequence-type ST198 strains, 44 belonged to the international monophyletic MDR lineage S. Kentucky ST198, and belonged to four separate sublineages, six strains occupying a basal position in relation to the MDR lineage. A total of 320 genes and mutations responsible for resistance to antimicrobial agents were identified. The most common were point mutations in the QRDR region. In most cases, Russian strains were characterized by the presence of variants of the SGI1-K genomic island. Moreover, the putative structure of SGI1 was correlated with the phylogenetic clustering of S. Kentucky sublineages.

Conclusions. The results of the study made it possible to assess the population structure of Russian S. Kentucky ST198 strains on a global scale and determine the genetic determinants of antibiotic resistance, including the structure of the SGI1 genomic island.

Introduction. Fluoroquinolones remain the key second-line anti-tuberculosis drugs.

The aim of the study was the molecular characterization of fluoroquinolone-resistant Mycobacterium tuberculosis strains from newly diagnosed tuberculosis patients in the Northwest of the Russian Federation.

Materials and methods. The retrospective study collection included M. tuberculosis isolates isolated in 2015–2019 from previously untreated tuberculosis patients. Susceptibility to antituberculosis drugs (including the fluoroquinolone ofloxacin) was determined using the BACTEC MGIT960 or absolute concentration method. Mutations in the gyrA gene as a marker of resistance to fluoroquinolones, were detected by real-time PCR. Beijing genotype and its subtypes were detected by PCR and real-time PCR methods. Non-Beijing strains were spoligotyped.

Results and discussion. Phenotypic resistance to ofloxacin was detected in 6.7% (40/599) of strains and in 17.4% (40/230) of MDR strains. 34 of 40 (85%) ofloxacin-resistant strains belonged to the Beijing genotype. 18 (45%) strains were assigned to the Russian epidemic subtype Beijing B0/W148 and 12 (30%) to Beijing Central Asian/Russian. The remaining 6 ofloxacin-resistant strains belonged to the Euro-American phylogenetic lineage. Mutations in the gyrA gene were found in 97.5% (39/40) of strains. The most common were mutations in codon 94 (69.2%, 27/39). The Asp94Gly substitution was identified in 57.5% (23/40) of ofloxacin-resistant strains and was dominant among Beijing (19/34) and non-Beijing (4/6) strains. The second most common substitution was Ala90Val (25%, 10/40). More than half of the ofloxacin-resistant strains, Beijing B0/W148 (10/18) and Central Asian/Russian (7/12), carried the Asp94Gly mutation.

Conclusion. In the Northwest of Russia in 2016-2019, primary resistance of M. tuberculosis to fluoroquinolones was 6.7% in the total collection and 17.4% of MDR strains, and was mainly caused by the gyrA Asp94Gly and Ala90Val mutations. Beijing B0/W148 genotype was characterized by the largest proportion of fluoroquinolone-resistant strains.

Introduction. Campylobacteriosis is among the leading causes of acute gastrointestinal infections. The severity of campylobacteriosis and the development of long-term complications may be influenced by the genotype of the pathogen, whose biological properties can affect immune response parameters.

The aim of the study was to identify common genotypes of epidemic clones of Campylobacter pathogens and to investigate characteristics of the immune response and severity of the disease.

Materials and methods. The study included 203 patients aged from 1 month to 17 years with campylobacteriosis who underwent treatment at the clinic of the Federal State Budgetary Institution "DNKCIB FMBA" in 2019–2021. The diagnosis was confirmed using polymerase chain reaction method. Patient samples were also analyzed using culture-based methods. Total DNA was extracted using the QIAamp DNA Mini Kit. Genetic determinants encoding virulence factors and MLST typing were performed using the ResFinder program. The immune status of patients was assessed on days 1 and 7 of the illness. Immunological investigation included measurement of serum immunoglobulin concentrations (IgA, IgM, IgG), C-reactive protein, and cytokines (IL-1β, IL-1, IL-2, IL-4, IL-5, IL-6, IL- 7, IL-8, IL-10, TNF-α, and IFN-γ).

Results. When analyzing the frequency of detection of Campylobacter sequence types in children with clinical intestinal infections, it was found that the profile of isolated isolates is most similar to those from countries of North America (USA and Canada), Northern Europe (Great Britain, Holland ) and Scandinavia (Denmark, Sweden, Finland). Identification of a pathogen with the flgE⁺, cdtA⁺, cdtC⁺ genotype was accompanied by a statistically significant increase in the level of IL-8 and a decrease in the content of IgA in the peripheral blood serum, which reflected the low efficiency of the immune response during infection with Campylobacter and predetermined the severe course of the infectious process during the disease.

Introduction. Based on data on the role of blood erythrocytes in the development and implementation of the vaccine and infectious processes in plague, it was of interest to evaluate changes in erythrocyte surface architecture from the position of searching for informative criteria for the preclinical evaluation of anti-plague vaccines.

Aim — using atomic force microscopy to characterize the state of the blood erythrocyte membrane of guinea pigs in response to subcutaneous administration of the vaccine strain Yersinia pestis EV NIIEG and its isogenic derivatives.

Materials and methods. For immunization of animals strain Y. pestis EV NIIEG (pYT⁺, pYV⁺, pYP⁺) and its isogenic derivatives Y. pestis KM216 (pYT^–, pYV^–, pYP⁺), Y. pestis KM217 (pYT^–, pYV⁺, pYP^–), Y. pestis KM218 (pYT^–, pYV^–, pYP^–) were used. Analysis of the erythrocyte membrane was carried out using a Solver P47-PRO scanning probe microscope (NT-MDT, Russia).

Results. The most pronounced changes in the surface architectonics of the membrane of guinea pig erythrocytes were established during the first three days of the formation of the immune response to the Y. pestis EV strain NIIEG and its isogenic variant Y. pestis KM217, in the genome of which the pYV plasmid is preserved, administered at a dose of 5 × 10⁸ CFU. A significant increase (p < 0.05) in the proportion of transformed cell forms (43.67 ± 3.63% and 37.83 ± 7.03% versus 4.08 ± 0.86% in the control group), root mean square roughness (319 ± 8 nm and 312 ± 7 nm versus 70 ± 6 nm in the control group), Young's modulus (125.73 ± 4.48 kPa and 113.8 ± 5.41 kPa versus 53.03 ± 1.47 kPa in the control group). By the 21^st day, the value of these indicators decreased by an average of 2.7, 2.0 and 1.5 times, respectively, indicating restoration of the erythrocyte membrane.

Conclusion. The dependence of the changes in the erythrocyte membrane and the rate of their restoration on the plasmid composition of Y. pestis strains has been established. The data obtained contribute to the understanding of the processes of interaction of Y. pestis with the erythrocyte membrane and can be used as additional characteristics in the development of new criteria for preclinical evaluation of plague candidate vaccines.

The aim of the review is to give a brief description of the biodiversity and structure of the hospital environment microbiome based on molecular genetic research methods.

Until a certain time, studies of the hospital environment microbiota for the purposes of epidemiological surveillance and control of healthcare-associated infections (HAIs) were based on routine microbiological identification of clinically relevant bacterial taxa. Discovery of DNA, the development of sequencing technologies, PCR and cloning techniques enabled the investigation of microbial communities using cultivation-independent, DNA and RNA-based approaches. At the current level of knowledge, the hospital environment can be considered as a superorganism with its own microbiome. Multiomic technologies, including meta-transcriptomic, meta-proteomic and metabolomic approaches, provide detailed information about microbial activity in the environment. Now it has been established that there is a stable core of the hospital microbiome where the vast majority of microorganisms are necessary for the functioning of the hospital ecosystem and are not classified as human pathogens. The hospital microbiome has a homogeneous structure composed by a massive dominance of a few taxa and microbial network with low connectivity forming a clustered topology. A keystone species is a taxon whose importance for maintaining community structure is relatively higher than others and its identification is of paramount importance. Due to the lack of knowledge of the hospital environment microbiome by molecular genetic technologies, there is no single shared point of view on the microbial diversity in different healthcare facilities. But there is no doubt that molecular genetic technologies will shed light on the evolution of hospital strains and determine which indicators are the most informative for monitoring and prognosis of HAIs.

Monoclonal antibodies are widely used in all fields of biology and medicine. The emergence and development of the technology for their production revolutionized immunology and allowed the creation of not only new diagnostic methods, but also many effective drugs. The purpose of our review is to analyze and summarize relevant data concerning the technology of obtaining monoclonal antibodies. We have analyzed information from 70 modern literary sources devoted to various methods of obtaining them. In this review, we tried to cover the entire range of methods used to obtain monoclonal antibodies today.