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The most important goal of medical microbiology in terms of treating infectious diseases nowadays and in the coming decades will be the development of antibacterial agents that are effective against resistant pathogens and reduce the selection of antimicrobial resistance. In this regard, along with the search for new classic antibiotics, it is necessary to develop alternative strategies. Virulence factors that determine the key stages of the infection process, both acute and chronic, including adhesins, toxins, bacterial quorum sensing, secretory systems, could be potential targets. The strategy for the development of antivirulence drugs is already showing its potential in the treatment of nosocomial, complicated and chronic infections as part of complex therapy and for prevention. The review presents the results of studies of drugs that have already shown efficacy in model infections in animals or have either passed to the stage of clinical trials or have already been registered. The development of effective combination therapy regimens will minimize the risks of acquiring resistance.

Type III Secretion System (TTSS) is a key pathogenicity factor of Pseudomonas aeruginosa. The suppression of the activity of TTSS would potentially allow block the infection independently on the presence of antimicrobial resistance. To study the role of TTSS P. аeruginosa in the development of nosocomial infections we characterized genes coding TTSS effector proteins and the activity of its secretion in vitro in 75 P. аeruginosa isolates. Genes of TTSS effectors were detected in all studied isolates with exoS+-genotype being the predominant one (80%). Isolates with exoU+-genotype were revealed twice more frequent from urine and blood than from respiratory material: 26.5% vs 12.8%. The presence of functional TTSS during the induction by low calcium concentrations was observed for 60.4% of isolates. At the same time 76.6% of strains were highly cytotoxic in vitro. Exploring the relation of TTSS-genotypes with resistance to particular groups of antimicrobials has shown higher resistance rates to gentamicin and ciprofloxacin in exoU+-genotype. Overall we can conclude that TTSS is a potentially interesting target for control of infections caused by multi-resistant P. аeruginosa strains.

Antibiotic resistance is one of the most serious global health threats. Therefore, there is a need to develop antimicrobial agents with new mechanisms of action. Targeting of bacterial cystathionine γ-lyase (bCSE), an enzyme essential for bacterial survival, is a promising approach to overcome antibiotic resistance. Here, we described a series of (heteroarylmethyl)benzoic acid derivatives and evaluated their ability to inhibit bCSE or its human ortholog hCSE using known bCSE inhibitor NL2 as a lead compound. Derivatives bearing the 6-bromoindole group proved to be the most active, with IC 50 values in the midmicromolar range, and highly selective for bCSE over hCSE. Furthermore, none of these compounds showed significant toxicity to HEK293T cells. The obtained data were rationalized by ligand-based and structure-based molecular modeling analyses. The most active compounds were also found to be an effective adjunct to several widely used antibacterial agents against clinically relevant antibiotic-resistant strains of such bacteria as Staphylococcus aureus , Klebsiella pneumoniae , and Pseudomonas aeruginosa . The most potent compounds, 3h and 3i, also showed a promising in vitro absorption, distribution, metabolism, and excretion (ADME) profile. Finally, compound 3i manifested potentiating activity in pneumonia, sepsis, and infected-wound in vivo models.

Bacterial infections represent an unsolved problem today since bacteria can evade antibiotics and suppress the host's immune response. A family of TRIM proteins is known to play a role in antiviral defense. However, the data on the involvement of the corresponding genes in the antibacterial response are limited. Here, we used RT-qPCR to profile the transcript levels of TRIM genes, as well as interferons and inflammatory genes, in human cell lines (in vitro) and in mice (in vivo) after bacterial infections caused by Pseudomonas aeruginosa and Chlamydia spp. As a result, the genes were identified that are involved in the overall immune response and associated primarily with inflammation in human cells and in mouse organs when infected with both pathogens ( TRIM7 , 8 , 14 , 16 , 17 , 18 , 19 , 20 , 21 , 47 , 68 ). TRIMs specific to the infection ( TRIM59 for P. aeruginosa , TRIM67 for Chlamydia spp.) were revealed. Our findings can serve as a basis for further, more detailed studies on the mechanisms of the immune response to P. aeruginosa and Chlamydia spp. Studying the interaction between bacterial pathogens and the immune system contributes to the search for new ways to successfully fight bacterial infections.

Metal-organic framework nanoparticles (nanoMOFs) are promising nanomaterials for biomedical applications. Some of them, including biodegradable porous iron carboxylates are proposed for encapsulation and delivery of antibiotics. Due to the high drug loading capacity and fast internalization kinetics, nanoMOFs are more beneficial for the treatment of intracellular bacterial infections compared to free antibacterial drugs, which poorly accumulate inside the cells because of the inability to cross membrane barriers or have low intracellular retention. However, nanoparticle internalization does not ensure their accumulation in the cell compartment that shelters a pathogen. This study shows the availability of MIL-100(Fe)-based MOF nanoparticles to co-localize with Chlamydia trachomatis , an obligate intracellular bacterium, in the infected RAW264.7 macrophages. Furthermore, nanoMOFs loaded with photosensitizer methylene blue (MB) exhibit complete photodynamic inactivation of C. trachomatis growth. Simultaneous infection and treatment of RAW264.7 cells with empty nanoMOFs resulted in a bacterial load reduction from 100 to 36% that indicates an intrinsic anti-chlamydial effect of this iron-containing nanomaterial. Thus, our findings suggest the use of iron-based nanoMOFs as a promising drug delivery platform, which contributes to antibacterial effect, for the treatment of chlamydial infections.

The technology for the generating of single-domain recombinant monoclonal antibodies (nanoantibodies) based on the immunization of a camel, cloning of induced sequences encoding single-domain antigen-recognizing fragments of non-canonical camel antibodies, as well as functional selection of clones of nanoantibodies by the phage display method, was used to obtain new effective tools for more efficient diagnostics of Chlamydia infection and to develop new approaches for effective therapy. Two promising nanoantibodies were obtained. They showed effective binding to extracellular and intracellular forms of C. trachomatis, and also had activity that inhibited the development of chlamydial infection in vitro.

Sex-related infections are a global problem. Such infections may lead to acute or chronic diseases. Chlamydia trachomatis is a dangerous and widespread pathogenicity factor that is not sensitive to conventional drugs and has no obvious symptoms. Protein CPAF is leading factor of pathogenesis. This protein inhibits the signaling pathways of host cell and supports long survival of the pathogen in the host cell. The goal of this work was to review general properties of the proteasome Chlamydia protein CPAF, its functions, and role in pathology. The role of protein CPAF in the anti-chlamydia immune reaction is discussed. The prospects of the development of promising anti-chlamydia vaccine, as well as new effective anti-chlamydia drugs are also discussed.

Identification of biomarkers in multiple sclerosis is a very complex problem, and intensive work is being made in this field for the last decades. The importance of establishing biomarkers of multiple sclerosis is related to the high disease heterogeneity and lack of characteristic symptoms that leads to diagnostic, prognostic challenges and difficulties in making decisions about therapy. In this paper, we review the most important biomarkers and discuss their diagnostic and prognostic value. Experimental results on neurofilament heavy chains and antibodies to sulfatide in multiple sclerosis are presented.

Aim: Develop in vitro model for studying production of cytokines by monocyte cells infected with Chlamydia trachomatis mediated by type III secretion system (TTSS)., Materials and Methods: Strain C. trachomatis L2/434/Bu was used in the experiments, culture of human monocytes U-937 was infected by this strain. Level of inflammatory cytokines was measured on flow analyzer Bio-Plex 200 (Bio-Rad Laboratories). Low molecular compound LHC-342 which belongs to the class of heterocyclic compounds was used as TTSS inhibitor., Results: 24 hours after the infection with C. trachomatis culture 8 analyzed cytokines are induced in U-937 cells (IL-1beta, IL-4, IL-6, IL-8, IL-10, GM-CSF, IFN-gamma, TNFalpha). The most pronounced increase was observed for IL-8, GM-CSF and IFN-gamma. Introduction of TTSS inhibitor into the culture of infected cells suppressed chlamydia growth, but addition of FeSO4 restored the growth of chlamydiae. And activity associated with translocation of effector TTSS protein IncA to inclusion membrane was suppressed. Under the conditions of the obtained model of TTSS inhibition during intracellular development of C. trachomatis a significant decrease of 2 pro-inflammatory cytokines--IL-6 and IL-1beta--was observed., Conclusion: Cytokine response plays a key role in the protective immune response in chlamydia infection but at the same time induces immunopathologic conditions. The data obtained give reasons to assume role of C. trachomatis TTSS in the induction of this component of immune response that requires further detailed studies.

Aim: Comparison of features of recruitment to infection focus of cells mediating early immune reactions in intravaginally infected mice that had previously received or not received covinan (progesterone analogue)., Materials and Methods: A/Sn and BALB/c line mice were used in the study. C. muridarum strain Nigg infection was carried out intravaginally or intraperitoneally. For synchronization of sexual cycle a group of mice received subcutaneously a synthetic analogue of progesterone--proligeston (covinan) at a single dose of 33 mg/kg. Acute urogenital infection was evaluated by culture method. Quantitative determination of C. muridarum DNA (including study of persistence) was carried out by real time PCR. Subpopulation structure of cell population of peritoneal and vaginal lavage was evaluated by flow cytofluorometry., Results: Intravaginal infection of mice that had not received covinan resulted in a pronounced recruitment of cells into vaginal cavity at 24 hours after the infection. Influx of neutrophils, dendritic cells and T-lymphocytes was especially pronounced. Prior administration of covinan practically nullified cell recruitment to infection focus though partial preservation of subpopulations of activated dendritic cells and CD8+ T-cells was observed., Conclusion: In mice with artificially induced by progesterone sensitivity to chlamydias the ability of recruitment to the infection focus of cells that mediate early immune reactions is reduced, that gives evidence on the importance of these reactions for infection outcome.

Aim: Study microbicidal activity of low temperature argon plasma (LTP) that is a stream of partially ionized argon having macroscopic temperature of the environment against Chlamydia trachomatis obligate intracellular parasites. Study viability of host cells in parallel., Materials and Methods: McCoy line cells infected with C. trachomatis (Bu-434/L2 strain) were exposed to LTP obtained by using atmospheric pressure plasma SHF generator. Intracellular localization of chlamydiae was visualized by luminescent microscopy., Results: Exposure of infected McCoy line cells resulted in the destruction of chlamydia inclusions and practically complete elimination of intracellular bacteria. At the same time LTP exposure did not result in immediate death of host cells, an insignificant reduction of the number of cells was observed 24 hours after the exposure to LTP., Conclusion: The effect of LTP for elimination of intracellular chlamydia without significant changes in viability of eukaryotic host cells was demonstrated.

The role of the type-three secretion system of the gram-negative bacteria in regulation of chronic infections is discussed. Recent research showed that most of severe chronic somatic diseases are derived from chronic infection induced in the first place by infectious agents. The role of the T3SS of different species in transition from an acute infection to persistence is reviewed. Clinical and bacteriological research showed that microorganisms are persistent in the form resistant to antibiotics. That is why one of the promising targets for the development of antibacterial new-generation treatment is T3SS that conducts transport of bacteria pathogenicity factors into eukaryotic cell. The presence of this structure is necessary for the development of an acute infectious process and chronization of an infection is essential for its functioning.

Chlamydia trachomatis is one of the most widespread bacterial pathogens in the world that is transmitted sexually. Thereby a development of vaccine preparation for therapy and prophylaxis of infections caused by C. trachomatis is an actual topic of scientific research across the entire world. These vaccines could be used for both prophylaxis and therapy of already established chlamydia infection and, respectively, reduce the risk of chronic condition and prevent the spread of pathogen in the population. Features of chlamydia biology that are associated with obligate intracellular parasitism and immunopathologic state induced by this agent significantly complicate developments in this field. Currently a vaccine preparation that has reached clinical trials does not exist.

Global spread of clinically significant strains resistant to antibiotics necessitated the development of new approaches to generation of antibacterial preparations. Selection of virulence factors as targets for new preparations is an alternative approach to therapy of infections caused by resistant strains and chronic infectious diseases. Contemporary state of research aimed at target selection among virulence factors of pathogenic for humans bacteria that cause chronic infections, and screening of specific inhibitors of these targets are examined. Analysis of limited data of therapeutic activity of selected preparations, i.e. experimental confirmation of the proposed concept, is provided.

Persistence is a form of interaction of pathogenic bacteria with a host aimed to promote their long-term survivalby means of inactivation of the host's protective systems via modulation of intracellular signal pathways. Persistent forms of a pathogen are refractory to traditional antibiotic therapy and cause chronic infectious diseases. Directed search for protein targets and new antibacterial drugs using computer simulation and experimental testing for the development of innovative preparations to treat chronic bacterial infections appears to have good prospects as a method for the management of persistent infections. A stepwise strategy for realization of such approach is exemplified by the search of preparations against chlamydial infection.

The review summarizes the recent published data on molecular mechanisms of Chlamidiae - host cell interaction, first of all on chlamydial effector proteins. Such proteins as well as III transport system proteins that transfer many effector proteins into host cytoplasm are attractive targets for drug therapy of chlamydial infections. The majority of the data concerns two species, Chlamydia trachomatis and Chlamydophila pneumoniae. C. trachomatis protein TARP, which is presynthesized in elementary bodies, plays an essential role in the initial stages of the infection. Patogen proteins participating in the next stage, that is the intracellular inclusion traffic to the centrosome, are CT229 of C. trachomatis and Cpn0585 of C. pneumoniae, which interact with cellular Rab GTPases. In C. trachomatis, IncA protein plays a key role in chlamydial inclusions fusion, CT847 modulates life cycle of the host cell, LDA3 is essential in acquisition of nutrients. CPAF protease and inclusion membrane proteins IncG and CADD participate in suppression of apoptosis of infected cells. The proteases CPAF and CT441, as well as deubiquitinating ChlaDub1 protein, contribute to avoiding the immune response.

Aim: To study the possible hematogenic route of dissemination of Chlamydia trachomatis and to analyze efficacy of methods of pathogen detection in clinical specimens (sera and scraping material)., Materials and Methods: Cultural method, electron microscopy, real-time PCR, immunofluorescent assay., Results: C. trachomatis was detected in blood by using 2 tests (culture and PCR) in 95.2% of patients with confirmed Chlamydia infection. Chlamydia isolated from blood had infectious properties that could point to the presence of weakly studied hematogenic route of dissemination of C. trachomatis in host's organism. Study of diagnostic value of pathogen detection in serum showed that in case of chronic diseases of urogenital tract as well as extragenital diseases, rate of C. trachomatis detection in serum was significantly higher (61.1% of cases compared to 16.7% in scraping material)., Conclusion: It is the first time when data about possible circulation of C. trachomatis in blood of patients was obtained. Detection of C. trachomatis in serum of patients with chronic and complicated forms of chlamydiosis provides essentially new approach for direct identification of the pathogen irrespectively from localization of infection's locus.