Pskov State University

Background: Antimicrobial resistance (AMR) is a global public health threat, with antiprotozoal resistance receiving less scrutiny, particularly in vulnerable populations. Patients with mental disorders, often on long-term psychotropic therapy, may have altered gut microbiomes that could predispose them to parasitic infections and drug resistance. Aim: This study aimed to investigate the prevalence of intestinal parasitosis and characterize Blastocystis hominis resistance to the antiprotozoal drugs metronidazole and trimethoprim in patients with mental disorders. Methods: A retrospective study was conducted by analyzing medical records of 40 patients from a psychiatric center. Intestinal parasitocenosis was assessed using bacterioscopic and culture methods on Jones' medium. The susceptibility of isolated Blastocystis hominis strains was determined by the standard disk diffusion method and by assessing the minimum inhibitory concentration (MIC). Results: Protozoal infections were detected in 27.5% (11/40) of patients, with Blastocystis hominis being the most prevalent (53.8% of positive cases). Among the isolated strains, 42.9% were sensitive to metronidazole and 57.1% to trimethoprim; the remaining strains were resistant. The MIC for metronidazole was 10-3 mg/m L, and for trimethoprim, 10-4 mg/mL. Conclusions: A high rate of antiprotozoal drug resistance in Blastocystis hominis was identified in this vulnerable population, potentially linked to antipsychotic-induced gut dysbiosis. The findings underscore the need for parasitic monitoring and susceptibility testing prior to empirical therapy in this group.

Background: Intestinal parasitic diseases, particularly blastocystosis caused by Blastocystis spp., represent a global health concern, affecting up to 80% of populations in developing countries. Understanding the functional digestive disturbances associated with this infection is crucial for diagnosis and treatment. Aim: This study aimed to investigate the structural and chemical changes in the gastrointestinal tract during Blastocystis spp. infection using comprehensive coprogram characteristics and to evaluate the diagnostic value of its indicators. Methods: A cross-sectional study was conducted on 503 individuals with gastrointestinal diseases and confirmed Blastocystis spp. infection, compared with 150 healthy controls matched by sex and age. Fecal samples were analyzed without prior dietary standardization, using four preparations: native, Lugol's solution, Sudan solution, and glycerin. Analysis included evaluation of detritus, muscle and plant fibers, starch, and protozoa identification. Results: Infected individuals showed significant digestive disturbances compared to controls. Reduced detritus content was observed in over 50% of infected individuals, indicating impaired digestion. Over 80% exhibited poorly digested cylindrical muscle fibers. Digestible plant fiber was significantly elevated, varying with stool consistency (p < 0.05). Complete absence of starch digestion was observed in 100% of infected individuals, with 56.85% showing significant amounts (++) and 43.15% very large amounts (+++), contrasting with 98% of controls with no detectable starch (p < 0.001). Discussion: The findings indicate that Blastocystis spp. infection causes profound alterations in digestive processes, characterized by fermentation and incomplete digestion of carbohydrates and proteins. Coprological examination proved to be a simple, highly valuable diagnostic tool for detecting these functional disorders. Conclusions: Coprogram indicators serve as effective laboratory instruments for diagnosing parasitic diseases like blastocystosis and can guide therapeutic strategies in clinical practice.

This paper analyses the role of ticket flexibility in revenue management and competitive strategies within highspeed rail (HSR) markets. By considering the relevance of duopolistic settings in the EU markets, we develop a two-firm theoretical model incorporating operator-based and ticket-based competition, which encompasses ticket flexibility options. The model captures key features of liberalized HSR markets where incumbent operators typically offer higher service frequencies while new entrants face capacity constraints and must strategically utilize flexibility policies to compete. Using a Hotelling framework extended to include stochastic ticket availability, we show that the type of competition might critically depend on passengers' disutility due to inflexible tickets and the probability that promotional fares sell out before departure. We calibrate the theoretical model using comprehensive real-time data from the Italian HSR market, tracking ticket fares and availability for Trenitalia and NTV Italo across eight major routes over four months. Besides estimating the probability that entrants exhaust discounted tickets before incumbents through survival analysis of booking patterns, the empirical analysis unveils distinct competition patterns by ticket classes and routes characteristics, as 2nd-class markets and/or long-distance popular routes exhibit ticket-based competition where flexibility implies price premiums, while 1st-class markets and/or short-haul and less demanded city connections display operator-based competition focused on operator characteristics rather than ticket types. Results suggest that, when passengers are weakly sensitive to ticket inflexibility, entrants adopt aggressive pricing across all fares, leading to operator-based competition. By contrast, when flexibility is highly valued, the operators reduce promotional ticket prices while keeping premium pricing for flexible options, resulting in ticket-based competition. These findings have implications for revenue management strategies in HSR markets and suggest that regulatory policies affecting ticket flexibility should be tailored to specific rail sub-markets.

IntroductionThis study compares two asymmetrical security models in Eurasia: Europe’s NATO-centered security architecture, which relies on extended nuclear deterrence, and Kazakhstan’s institutionalized strategy of denuclearization.MethodsThe theoretical framework is grounded primarily in classical realism, especially Morgenthau’s state-centric understanding of power and national interest, while Aron’s work is used to clarify the relationship between military force and diplomacy. The study uses structured qualitative comparative case study supported by descriptive quantitative indicators for the period 1991–2025. The empirical basis includes indicators of global nuclear arsenals, defense expenditure, and institutional security assessments drawn from standardized international datasets.ResultsThis article argues that nuclear deterrence and denuclearization represent structurally distinct security logics rather than comparable variants. While European security remains embedded in extended deterrence structures mediated through NATO and key nuclear states, Kazakhstan’s security model is based on strategic denuclearization and multilateral non-proliferation commitments.DiscussionThe comparison demonstrates that these models reflect different positions within the global nuclear order rather than alternative implementations of a single deterrence framework. The article contributes by reframing the comparison as one between Europe’s NATO-centered security architecture and Kazakhstan’s denuclearized security model. Rather than comparing equivalent political actors, the study compares two distinct forms of institutional embeddedness within the global nuclear order.